Science calculators

Grams to Moles Calculator

Convert mass (grams) to moles using the formula n = m / M. Pick from 16 preset substances or enter a custom molar mass. Bidirectional and in…

Velocity Calculator

Velocity calculator for three kinematics formulas: distance/time, initial velocity + acceleration, and the v-squared equation. Converts m/s …

Acceleration Calculator

Acceleration calculator covering four modes — velocity-time, Newton's second law (F = ma), free fall on Earth/Moon/Mars, and 0-60 mph …

Watt Calculator (P = V x I)

Compute electrical power three ways: P = VI, P = V^2/R, or P = I^2R. Enter any two of voltage, current, or resistance and the calculator pic…

Dog Size Calculator

Estimate adult dog size from a puppy's current weight and age. The calculator uses WALTHAM growth-percentage milestones by breed-size catego…

Density Mass Volume Calculator

Solve any of the three variables in ρ = m/V. Supports kg/m³, g/cm³, lb/ft³, common materials (water, aluminum, iron, gold), and full unit co…

Power-to-Weight Ratio Calculator

Compute the power-to-weight ratio (PWR) for vehicles, motorcycles, or cyclists. Supports HP, kW, W input and lb, kg, tonne mass, with output…

P-Value Calculator

P-value calculator for z-tests and t-tests. Enter the test statistic, pick one- or two-tailed, set degrees of freedom for t-tests, and get t…

Dog Pregnancy Calculator

Track canine pregnancy from breeding to whelping. Standard gestation is 63 days, with a 58 to 68 day window. The calculator returns the due …

Critical Value Calculator

Compute critical values for hypothesis tests across z, t, chi-square and F distributions. Standard alpha presets (0.10, 0.05, 0.01) plus cus…

Mole Calculator

Convert mass, moles, and particle count in any direction. Pick from 14 preset substances or enter your own molar mass. Uses the exact Avogad…

Kg to Newtons Converter

Compute weight in newtons from mass in kilograms using F = m × g. Earth uses standard gravity 9.80665 m/s². Switch to Moon, Mars, Jupiter, o…

Wet Bulb Temperature Calculator

Compute wet bulb temperature (Tw) from dry-bulb T and RH using the Stull 2011 empirical formula. Valid for –20 to +50 °C and 5–99 % RH. Heat…

Potential Energy Calculator

Potential energy calculator with gravitational mode (mgh) and elastic mode (½kx²). Includes planet presets for g and reports the…

T-Statistic Calculator

Compute the one-sample t-statistic, degrees of freedom (n-1), and two-tailed p-value from Student's t distribution. Same math used by R's t.…

Wave Speed Calculator

Wave speed calculator using v = f × λ. Returns the propagation speed of any wave — sound, light, water — in six use…

Standard Deviation Calculator

Standard deviation calculator for a list of numbers. Paste comma- or line-separated values and get the sample SD (n-1), population SD (n), v…

Coin Flip Probability Calculator

Coin flip probability calculator for any number of flips up to 10,000. Enter the flip count and desired heads, and get P(X = k), P(X ≥ k)…

Wavelength Calculator

Wavelength calculator using λ = v / f. Built-in presets for the speed of light in common media and the speed of sound in air, seawate…

Specific Heat Calculator

Solve the heat equation Q = mcΔT for any of the four variables: heat, mass, specific heat, or temperature change. Includes a material …

Tension Calculator

Compute rope or cable tension in newtons, kgf, and lbf. Four scenarios cover hanging mass (T = m(g+a)), inclined plane, Atwood pulley, and h…

Air Density Calculator

Compute air density from pressure, temperature, and humidity. Uses the ideal gas law for dry and moist air with Magnus saturation vapour pre…

Cat Age Calculator

Convert your cat's age to human-equivalent years with the veterinary standard formula. Year 1 = 15 human years, year 2 brings it to 24, then…

Dice Probability Calculator

Compute exact dice probabilities for any number of dice and sides. Supports d4, d6, d8, d10, d12, and d20. Returns the chance of an exact su…

Degrees of Freedom Calculator

Calculate degrees of freedom for one-sample t-tests, two-sample t-tests, chi-square independence, one-way ANOVA, and linear regression.

Probability Calculator

Compute basic probability, union P(A∪B), intersection P(A∩B), conditional P(A|B), and at-least-one probability across n trials. The calculat…

Flow Rate Calculator

Compute volumetric flow rate from volume and time, or from pipe diameter and velocity. Supports SI and US units. Output in L/min, GPM US, CF…

Relative Humidity Calculator

Compute relative humidity (RH) using the Magnus saturation vapour pressure equation. Inputs: air temperature plus either dew point or actual…

Chemical Equation Balancer

Balance chemical equations using matrix nullspace. Enter an unbalanced reaction (e.g. H2 + O2 -> H2O), get the smallest positive-integer …

Wire Size Calculator

Determine the minimum AWG conductor for a circuit using voltage drop and NEC 310.16 ampacity. Inputs: current, voltage, one-way run length, …

Cat Benadryl Dosage Calculator

Compute the safe diphenhydramine dose for a cat by body weight: 1 mg/lb every 8 to 12 hours, max three doses in 24 hours. Outputs both milli…

Dice Average Calculator

Compute expected average, minimum, maximum, and standard deviation for any dice roll (NdS with modifier). Supports d4, d6, d8, d10, d12, d20…

Gravitational Force Calculator

Gravitational force calculator using Newton's law of universal gravitation. Computes the attractive force between any two masses at any sepa…

Dew Point Calculator

Calculate dew point temperature from air temperature and relative humidity using the Magnus formula (Alduchov-Eskridge coefficients). Accura…

Watt-Hours Calculator

Convert between battery capacity ratings using Wh = V x Ah. Solves for any of the three variables and shows kWh, joules, and BTU equivalents…

Z-Score Calculator

Convert a raw value, mean, and standard deviation into a z-score. Returns percentile, normal CDF, two-tailed p-value, and outlier classifica…

Frequency Calculator

Frequency calculator with four input modes: from period (1/T), from wave speed and wavelength (v/λ), from angular frequency (ω/…

Soil Calculator

Compute soil volume needed for raised beds, gardens, and landscaping. Choose rectangular, circular, or triangular shapes. Outputs cubic yard…

Kinetic Energy Calculator

Kinetic energy calculator covering linear motion (KE = ½mv²) and rotational motion (KE = ½Iω²). Outputs joules…

Percent Yield Calculator

Calculate percent yield from actual and theoretical yields, or solve for any of the three variables. Includes yield-quality rating from exce…

Roulette Payout Calculator

Compute roulette payout, win probability, and expected value for any bet type on European (37 numbers) or American (38 numbers) wheels. Show…

LC Resonant Frequency Calculator

Compute the resonant frequency of an inductor-capacitor (LC) tank circuit. Solve for any of f, L, or C with full SI prefix support from nH t…

Parallel Resistor Calculator

Calculate the total resistance of 2 to 6 resistors connected in parallel using 1/R_total = sum(1/R_i). Result is always less than the smalle…

Angular Velocity Calculator

Compute angular velocity from RPM, frequency (Hz), period, or linear velocity. Output covers rad/s, RPM, Hz, period, °/s, plus tangential ve…

Combination Calculator

Calculate C(n, k) = n! / (k!(n-k)!) using exact BigInt arithmetic. Also returns permutations P(n, k) and odds-of-one for lottery-style probl…

Earth Curvature Calculator

Calculate Earth's curvature drop over a given distance, or horizon distance from a given observer height. Uses NASA mean Earth radius 3,959 …

Median Calculator

Compute the median of a list of numbers — the middle value when the data is sorted. Robust to outliers, unlike the mean. The calculato…

pH Calculator

Calculate pH from hydrogen-ion concentration, hydroxide concentration, or pOH. Returns the full set of values plus an acid-base classificati…

Torque Calculator

Torque calculator for rotational force. Use Newton's formula τ = F × r × sin(θ) with force, lever arm, and angle. Retu…

BTU to Tons Converter

Convert cooling capacity between BTU per hour and tons of refrigeration using the exact 1 ton = 12,000 BTU/hr definition adopted by ASHRAE f…

Engine Displacement Calculator

Compute engine displacement from bore, stroke, and cylinder count using the standard SAE formula. Returns cubic centimeters, liters, and cub…

Specific Gravity Calculator

Compute specific gravity from a substance density, with optional reference fluid (water at 4 °C by default). API gravity for petroleum and B…

HP to Amps Calculator

Calculate motor full-load amps from horsepower using I = (HP × 746) / (V × phase × eff × PF). Supports single-phase,…

Empirical Rule Calculator (68-95-99.7)

Apply the 68-95-99.7 rule. Enter mean and standard deviation; optionally enter a value to see its z-score and which standard-deviation band …

Force Calculator (F = ma)

Force calculator with two modes: F = m × a (Newton's second law) and weight = m × g for Earth, Moon, Mars or Jupiter. Reports th…

Ohm's Law / Resistance Calculator

Solve any leg of Ohm's law (V = IR). Enter two of voltage, current, or resistance and the calculator finds the third and computes power…

Molarity Calculator

Calculate molar concentration from mass or moles, find the mass needed for a target molarity, or run the dilution formula. Includes 11 prese…

Photon Energy Calculator

Compute photon energy from wavelength or frequency using E = hf and E = hc/lambda. Uses the exact 2019 SI values for Planck constant and the…

Concentration Calculator (Molarity, Molality, %, ppm)

Compute molarity, molality, mass percent (w/w), and ppm from solute mass, molar mass, solvent mass, and solution volume. Includes molar mass…

Free Fall Calculator

Calculate free-fall time, drop height, and impact velocity using h = ½gt² and v = gt. Choose Earth, Moon, Mars, or other planets. Ignores ai…

Ideal Gas Law Calculator (PV = nRT)

Solve PV = nRT for any unknown. Pick what you want to find, enter the other three, and the calculator returns pressure in atm, volume in lit…

Pie Chart Calculator (Percentages and Degrees)

Turn a list of categories and values into a pie chart with exact percentages and degree angles per slice. Add up to 12 categories, edit any …

Reynolds Number Calculator (Re = ρvL/μ)

Compute Re = ρvL/μ for pipe, external, or open channel flow. The calculator returns the Reynolds number, flow regime (laminar, transitional,…

Wavelength to Frequency Calculator

Convert between wavelength and frequency for electromagnetic waves (light, radio) or sound waves (air, water). Uses the speed of light c = 2…

Gear Ratio Calculator (Speed and Torque)

Gear ratio = driven teeth / driver teeth. Enter both tooth counts plus input rpm and torque. The calculator returns the ratio, output speed,…

Simpson's Diversity Index Calculator

Enter species abundance counts. The calculator returns Simpson's D (dominance), 1−D (diversity), 1/D (reciprocal), species richness, and eve…

T-Test Calculator (Two-Sample, Welch and Pooled)

Two-sample t-test calculator. Enter mean, standard deviation, and sample size for each group. Returns t, df, two-tailed p-value, Cohen's d, …

Enthalpy Calculator (ΔH = q at Constant Pressure)

At constant pressure, ΔH equals the heat exchanged q. Enter mass, specific heat capacity, and the temperature change. The calculator returns…

Lightning Distance Calculator

Flash-to-bang method for estimating distance to a lightning strike. Uses the speed of sound at your local temperature and shows risk level w…

pKa Calculator

Free pKa calculator with three modes: Ka to pKa, pKa to Ka, and Henderson-Hasselbalch buffer pH. Common acid presets included (acetic, phosp…

Water Density Calculator

Calculate water density as a function of temperature using the Tanaka 2001 and IAPWS-95 reference equations. Supports fresh water, seawater …

Relative Frequency Calculator

Enter any frequency table and instantly see relative frequencies, percentages, and cumulative relative frequencies. Handy for surveys, grade…

Terminal Velocity Calculator

Compute terminal velocity from mass, drag coefficient, and frontal area. Built-in presets for skydivers, raindrops, parachutes, spheres, and…

Average Atomic Mass Calculator

Compute the average atomic mass of an element from isotope masses and their natural abundances. Built-in presets (chlorine, copper, carbon, …

Least to Greatest Calculator

Paste any list and sort it ascending or descending. Accepts decimals (1.5), fractions (3/4), negatives, and scientific notation (1.5e-3). Ou…

Mass Percent Calculator

Solve any mass-percent problem in three modes: forward (calculate %), backward (find solute needed for a target %), or solvent (find how muc…

Vapor Pressure of Water Calculator

Apply the Antoine equation to find saturation vapor pressure of pure water. Enter temperature in °C; receive output in kPa, mmHg (torr), Pa,…

Acceleration from Force and Mass Calculator

Apply Newton's second law to compute acceleration from force and mass - or solve for either input. Includes conversions to lbf, kgf, dyne, a…

Buoyancy Calculator (Archimedes Principle)

Apply Archimedes principle to find buoyant force, apparent weight, and float-or-sink behavior. Choose fluid (water, sea water, mercury, air)…

Chemical Name Lookup (Formula ↔ Name)

Two-way dictionary for common chemicals: paste a formula (H2O, NaCl, CO2) to get the IUPAC and trivial names, or type a name to get the form…

Class Width Calculator

Find the class width for a histogram or frequency distribution. Enter min, max, and number of classes - or pick Sturges, Rice, or √n rules a…

Conductivity to Resistivity Calculator

Convert between electrical conductivity (σ in S/m) and resistivity (ρ in Ω·m) using the exact reciprocal relation ρ = 1/σ. Includes material…

Coulomb's Law Calculator

Apply Coulomb's law to find the electrostatic force between two point charges. Inputs: charge magnitudes (in C), distance (m), and dielectri…

Henderson-Hasselbalch Calculator

Compute buffer pH from pKa and acid/base concentrations using the Henderson-Hasselbalch equation. Switch modes to solve for [A−]/[HA] ratio …

Maximum Height Projectile Motion Calculator

Find the maximum height, time-to-peak, total flight time, and range of a projectile from initial speed and launch angle. Earth and other pla…

Point Estimate Calculator

Compute the point estimate of a population parameter from sample data. Supports sample mean (x̄) with t-based CI and sample proportion (p̂) …

Relative Error Calculator

Find the relative and percent error between a measured and a true value. Choose unsigned magnitude or signed direction to detect over- or un…

Volume to Mass Calculator

Compute mass from volume (or volume from mass) using density: m = ρ × V. Pick a substance - water, oil, metals, gasoline, milk - or enter cu…

Efficiency Calculator

Compute energy efficiency three ways: basic η = output/input, Carnot maximum from two reservoir temperatures, or COP for heat pumps and AC. …

Partial Pressure Calculator

Compute the partial pressure of a gas in a mixture two ways: Dalton's law from mole fraction and total pressure, or the ideal gas law from m…

Wavelength to Energy Calculator

Convert photon wavelength to energy with E = hc/λ. Enter wavelength, frequency, or energy in your choice of units and the calculator returns…

Wire Resistance Calculator

Compute the resistance of a wire from its material, length, and cross-section. Choose AWG gauge, area in mm², or diameter, and add a tempera…

Capacitive Reactance Calculator

Compute Xc = 1 / (2π f C) given any capacitance and signal frequency. Built-in unit selectors (pF, nF, µF, F; Hz, kHz, MHz, GHz) and instant…

Confidence Interval Calculator

Confidence interval for the mean (Student t-distribution) or for a proportion (normal approximation). Margin of error, critical value, and s…

Doppler Effect Calculator

Calculate the Doppler shift for sound waves (f′ = f (v ± v_obs) / (v ∓ v_src)) and electromagnetic waves (relativistic f′ = f √((1−β)/(1+β))…

Friction Loss Calculator

Compute pressure drop in a pipe from flow rate, diameter, and length. Pick Darcy-Weisbach (universal) or Hazen-Williams (water systems) - ou…

G-Force Calculator

Convert acceleration to g-force (multiples of Earth gravity, 9.80665 m/s²). Linear mode for straight-line braking and dragsters; centripetal…

Knowledge Base: Centripetal Force Calculator

NAGŁÓWEK

P-Hat Sample Proportion Calculator

Compute sample proportion (p̂), standard error, margin of error, and confidence interval from successes and sample size. Built-in normality …

Pipe Flow Calculator

Solve pipe-flow problems: Q = v·A, Re = ρvd/μ, and Δp = f (L/d) ρv²/2 by Darcy–Weisbach. Swamee–Jain explicit friction factor for turbulent …

PPM to Molarity Calculator

Convert PPM (mg/L) to molarity (mol/L) and back using the formula M = ppm · ρ / (M_w × 1000). Built-in densities for water, ethanol, methano…

Standard Temperature and Pressure Calculator

Compute molar volume and ideal-gas quantities for the four major standards: classic STP (0°C, 1 atm), IUPAC SATP (25°C, 1 bar), IUPAC 2019 S…

Water Viscosity Calculator

Look up dynamic viscosity η and kinematic viscosity ν of water from 0°C to 100°C with NIST/IAPWS-grade accuracy. Density included for kinema…

Magnitude of Acceleration Calculator

Calculate the magnitude (length) of an acceleration vector. Three modes: 2D components |a| = √(ax² + ay²), 3D components |a| = √(ax² + ay² +…

Normal Force Calculator

Calculate the surface contact (normal) force in four scenarios: flat surface (N = mg), incline (N = mg cos θ), elevator with vertical accele…

Angular Frequency Calculator

Convert between angular frequency ω (rad/s), ordinary frequency f (Hz), period T, and RPM. Uses ω = 2πf = 2π/T = πn/30. Handy for AC circuit…

Light Year Calculator

Convert astronomical distances between light-years (ly), parsecs (pc), AU, kilometers, miles, meters, and light-seconds/minutes/hours. Uses …

Capacitor Energy Calculator

Compute the energy stored in any capacitor with E = ½CV². Pick capacitance in F, µF, nF or pF and voltage in V or kV. The tool shows joules,…

Bullet Energy Calculator (Muzzle Energy)

Find bullet muzzle energy in foot-pounds and joules. Enter grains and fps. Quick presets for .22 LR, 9mm, .45 ACP, .308, .50 BMG.

Implied Probability Calculator

Convert betting odds to implied probability in seconds. Decimal, American and fractional formats supported. Add the other side to strip the …

Boiling Point Calculator (Altitude & Pressure)

Find the boiling point of water at any altitude or atmospheric pressure. Enter meters, feet or hPa. Quick-pick Denver, Mexico City, Everest,…

Resultant Force Calculator (Vector Sum)

Find the resultant of multiple forces with this 2D vector sum tool. Enter 2 to 4 forces by magnitude (N) and angle (°). Result includes Cart…

Contact Lens Vertex Distance Calculator

Convert spectacle prescription to contact lens power using the vertex distance formula. Critical for prescriptions above ±4.00 diopters.

Residual Calculator (Observed − Predicted)

Compute the residual of a regression: e = observed − predicted. Single-point mode or paste multiple pairs to get SSR, MAE, RMSE and R².

Theoretical Yield Calculator (Stoichiometry)

Compute the theoretical yield of a chemical reaction from limiting reagent mass, molar masses and stoichiometric coefficients. Optional actu…

Arrow Speed Calculator

Estimate arrow speed (FPS) from your bow's IBO rating, draw weight, draw length, and arrow grain weight. Includes kinetic energy and momentu…

Sound Wavelength Calculator

Compute the wavelength of a sound wave using λ = v / f. Air speed adjusts for temperature; presets cover seawater, steel, wood, and other me…

Watts to Amps Calculator

Convert watts to amps across DC, single-phase AC, and three-phase AC circuits. Includes power factor for AC and recommended breaker sizing.

90% Confidence Interval Calculator

Compute a 90% confidence interval for a population mean using x̄ ± 1.645 · σ/√n. Supports 80%–99.9% levels with their standard z-scores.

DC Wire Size Calculator

Pick the right AWG gauge for your DC circuit. Inputs: current, voltage, one-way length, allowed voltage drop, copper or aluminum. Outputs re…

Mean, Median, Mode Calculator

Paste a list of numbers and instantly get mean, median, mode, range, and standard deviation. Handles up to thousands of values. Skewed and u…

Drag Equation Calculator

Compute aerodynamic drag force from density, velocity, frontal area, and drag coefficient. Includes power-to-overcome-drag and presets for c…

Belt Length Calculator

Calculate the length of a drive belt running over two pulleys. Supports open and crossed configurations, wrap angles, and 3–5% margin for st…

Moles to Atoms Calculator

Convert between moles and number of particles using Avogadro's constant N_A = 6.02214076 × 10²³ mol⁻¹. Exact SI definition since 2019. Forwa…

Foot-Pounds of Energy Calculator

Find foot-pounds of energy for any projectile. Enter mass (grains, grams, ounces) and velocity (fps, m/s, mph). Returns ft·lb, joules, and c…

Net Ionic Equation Calculator

Generate the net ionic equation from a balanced molecular equation. Splits aqueous strong electrolytes into ions, removes spectators, and sh…

Boiling Point at Altitude Calculator

Find the boiling point of water at any altitude in °C, °F, or K. Uses the barometric formula plus Antoine equation. Presets for Denver, Mexi…

Charles Law Calculator

Apply Charles law to find any of V₁, V₂, T₁, T₂. Inputs in any temperature and volume units. Returns volume change, temperature ratio, and s…

Energy to Wavelength Calculator

Find photon wavelength from energy. Input eV, keV, MeV, J, kJ/mol, or kcal/mol. Returns λ in nm/Å/μm/m, frequency in Hz, and EM-spectrum cla…

Z-Test Calculator

Run a one-sample z-test. Enter sample mean, hypothesised population mean, population σ, and sample size. Returns z-statistic, p-value, stand…

Electrical Power Calculator

Calculate electrical power, voltage, current, or resistance using Ohm and Joule laws. Six input modes. Returns watts, kilowatts, horsepower,…

Hypergeometric Distribution Calculator

Find the probability of k successes in n draws without replacement. Returns PMF, CDF, upper-tail probability, mean, variance, and σ for any …

Acceleration Due to Gravity Calculator

Find g for any planet, altitude, or latitude. Uses Newton law of gravitation plus centrifugal correction at rotating-body latitudes. Include…

Stopping Distance Calculator

Find vehicle stopping distance with reaction time and braking distance. Surface presets for dry, wet, snow, ice. Returns metres, feet, time …

kVA Calculator (Apparent Power, 1-Phase & 3-Phase)

Calculate apparent power in kilovolt-amperes (kVA) from voltage and current. Switch between single-phase (V × I / 1000) and three-phase (√3 …

Activation Energy Calculator (Arrhenius)

Calculate activation energy (Ea) from two rate constants at two temperatures using the Arrhenius equation. Returns Ea in kJ/mol, kcal/mol, J…

Activity Coefficient Calculator (Debye-Hückel)

Calculate ion activity coefficient γ from ionic strength and ion charge. Supports Debye-Hückel limiting law (I < 0.01 M), Güntelberg extende…

Actual Yield Calculator

Compute actual yield, theoretical yield, or percent yield using the relationship actual = (percent / 100) × theoretical. Includes loss track…

Air Fuel Ratio Calculator (AFR)

Compute the air-fuel ratio (AFR) and lambda coefficient for any fuel. Identify rich, stoichiometric, and lean mixtures. Built for engine tun…

Alligation Calculator

Solve alligation alternate problems. Enter two strengths and a target, get the parts ratio plus the exact volumes that mix to the desired co…

Arrhenius Equation Calculator

Compute the rate constant, activation energy, or pre-exponential factor with the Arrhenius equation. Four solve-for modes including the two-…

Atom Calculator

Count atoms in any mass using Avogadro's number, or compute subatomic particles (protons, neutrons, electrons) for an isotope. 25 element pr…

Atom Economy Calculator

Compute atom economy from molecular weights of products or reactants. The 2nd principle of green chemistry, this measures how many atoms fro…

Atomic Mass Calculator

Compute the atomic mass of an element from its isotopic composition. Up to 4 isotopes, with abundance validation (sum to 100%). Output in un…

Avogadro Calculator

Avogadro calculator: convert between moles, particles (atoms or molecules), and mass for any substance. Six bidirectional modes built on N_A…

Beer-Lambert Law Calculator

Solve A = εlc for any variable in UV-Vis spectrophotometry. Five modes including transmittance-to-absorbance conversion. Built for analytica…

Bleach Dilution Calculator

Calculate how much household bleach to mix with water to reach a target free-chlorine concentration. CDC and WHO ppm targets included. Built…

Boiling Point Elevation Calculator

Compute the boiling-point elevation of a solution from molality, the ebullioscopic constant Kb, and the van't Hoff factor i. Includes Kb pre…

Bond Order Calculator

Compute bond order from molecular orbital electron counts. BO = (Nb − Na) / 2. Includes presets for common diatomics - H2, N2, O2, fluorine,…

Buffer Capacity Calculator

Compute the buffer capacity β in mol/(L·pH) using the Van Slyke equation. Maximum β occurs at pH = pKa, where β ≈ 0.576·C. The calculator in…

Buffer pH Calculator

Calculate buffer pH with the Henderson-Hasselbalch equation. Three modes: pH from [A−]/[HA], required ratio for a target pH, or actual [HA] …

Calibration Curve Calculator

Build a linear calibration curve from standards: paste x,y pairs and the calculator fits y = m·x + b using ordinary least squares. Returns s…

Carbon-14 Dating Calculator

Compute the age of an organic sample from the fraction of carbon-14 remaining, or vice versa. Uses the Libby-corrected C-14 half-life of 573…

Chemical Oxygen Demand (COD) Calculator

Compute chemical oxygen demand (COD) from the dichromate back-titration with ferrous ammonium sulfate. Standard formula: COD (mg O₂/L) = (V_…

Combustion Analysis Calculator

Determine the empirical formula of an organic compound from combustion data. Enter sample mass, CO₂ produced, and H₂O produced. The calculat…

Combustion Reaction Calculator

Balance complete-combustion equations for any hydrocarbon CxHy. The calculator returns the balanced equation, moles of O₂ consumed, CO₂ and …

Crude Protein Calculator

Calculate crude protein (%CP) from nitrogen content using the Kjeldahl conversion factor. The default factor is 6.25 (general feed and meat)…

Cubic Cell Calculator (SC, BCC, FCC)

Compute crystal structure properties for simple cubic, body-centered cubic (BCC), and face-centered cubic (FCC) unit cells. Outputs atoms pe…

Degree of Unsaturation Calculator

Calculate the degree of unsaturation (also called DBE or IHD) from molecular formula. Enter carbon, hydrogen, nitrogen, halogen counts and n…

Detention Time Calculator (HRT, t = V/Q)

Compute hydraulic retention time (HRT) for clarifiers, aeration tanks, and reservoirs from the V/Q formula. Solve for time, volume, or flow …

Diffusion Coefficient Calculator

Calculate the diffusion coefficient D from Stokes-Einstein relation for liquids, or the rate ratio of two gases by Graham law. Reports D in …

Dilution Factor Calculator

Compute dilution factor from sample and diluent volumes, plan serial dilutions across multiple steps, or solve C1V1 = C2V2 for stock volume.…

Double Bond Equivalent Calculator (DBE)

Compute the double bond equivalent (DBE), also called degree of unsaturation, from any molecular formula. Returns the count of rings plus π …

Effective Nuclear Charge Calculator (Z_eff)

Calculate effective nuclear charge Z_eff using Slater rules for any electron in any element from hydrogen through barium. Outputs shielding …

Electrolysis Calculator (Faraday Law)

Compute the mass of metal deposited during electrolysis from current, time, molar mass, and electron count using Faraday law. Solve for any …

Electromotive Force (EMF) Calculator

Compute electromotive force of a galvanic cell from standard reduction potentials. Includes the Nernst equation for non-standard concentrati…

Electron Configuration Calculator

Enter an element symbol (Fe), name (iron), or atomic number (26) to get the full electron configuration in spdf notation and the noble-gas s…

Electron Configuration Quiz

Drill the Aufbau order, noble-gas shorthand, half-filled d exceptions (Cr, Cu), and ion configurations. Each question shows the element or i…

Electronegativity Calculator

Pick two atoms from a built-in Pauling-scale table, see ΔEN, the percent ionic character (Pauling 1939 formula), and a bond-type label…

Empirical Formula Calculator

Enter the mass percent of each element. The calculator divides by atomic mass, normalizes by the smallest result, multiplies up to integers,…

Entropy Calculator

Switch between three entropy modes: reversible heat divided by temperature, Boltzmann S = k ln W from microstates, and standard reaction ent…

Enzyme Activity Calculator

Enter V_max, K_M, and substrate concentration. The calculator returns initial velocity v₀, percent of V<sub>m…

Equilibrium Constant Calculator

Enter coefficients and equilibrium concentrations for each reactant and product. The calculator multiplies them raised to their stoichiometr…

Freezing Point Depression Calculator

Choose your solvent (with its K_f auto-filled), choose your solute (with its van’t Hoff factor i), enter molality. The calcu…

Gibbs Free Energy Calculator

Enter ΔH (kJ/mol), ΔS (J/(K·mol)), and T. The calculator returns ΔG, ln K and K from ΔG° = −RT ln K…

Gibbs Phase Rule Calculator

Calculate degrees of freedom (F) using Gibbs phase rule F = C − P + 2. Handles normal, isobaric, isothermal, and condensed systems.

Graham’s Law of Diffusion Calculator

Pick two gases (or enter custom molar masses) and the calculator returns the rate ratio r₁/r₂ from Graham’s law,…

Half-Life Calculator

Enter initial amount, half-life with its unit, and elapsed time. The calculator returns N(t), percent remaining, number of half-lives, decay…

Heat of Combustion Calculator (ΔH_c, kJ/mol, kJ/g)

Compute the total heat released by combustion using moles times ΔH per mole. Picks for methane, propane, ethanol, octane, hydrogen and more,…

Hydraulic Retention Time Calculator (HRT = V/Q)

Hydraulic retention time tool for wastewater and water treatment design. Compute HRT, required volume, or required flow rate, with unit sele…

Hydrogen Ion Concentration Calculator (pH ↔ [H⁺])

Hydrogen ion concentration converter: pH ↔ [H⁺], pOH ↔ [OH⁻], with Kw cross-check and acid/base classification. Works for water-based soluti…

Ionic Strength Calculator (I = ½ Σ cᵢzᵢ²)

Ionic strength tool for chemistry, biology, and environmental engineering. Add up to six ion species, choose presets like 0.1 M CaCl₂ or sea…

Isoelectric Point Calculator (pI from pKa values)

Two-mode pI calculator: single amino acid (uses average of relevant pKa) and protein from residue counts (iterative net-charge zero). EMBOSS…

Kp Equilibrium Constant Calculator (Partial Pressures)

Equilibrium constant Kp calculator with stoichiometric coefficients and partial pressures. Reports Kp, log Kp, Δn, and direction of equilibr…

Langmuir Isotherm Calculator (θ, qₑ, R_L)

Langmuir adsorption isotherm tool for solid-liquid and gas-solid systems. Three modes: fractional coverage, equilibrium loading from concent…

Lattice Energy Calculator (Born-Haber + Kapustinskii)

Lattice energy calculator with two approaches: Kapustinskii estimate from charges and radii (NaCl, MgO, CaF₂), and full Born-Haber cycle fro…

Liquid Ethylene Density Calculator (kg/m³ vs Temperature)

Liquid ethylene density tool covering −169 °C (triple point) to 9 °C (critical point). Interpolates NIST saturated-liquid data and returns d…

Michaelis-Menten Equation Calculator (v, V_max, K_M)

Michaelis-Menten enzyme kinetics calculator. Pick the unknown (v, [S], V_max, K_M), enter the others, get velocity, percent saturation, and …

Miller Indices Calculator

Convert plane intercepts to Miller indices (hkl), get intercepts back from indices, and calculate d-spacing for cubic crystals using d = a /…

Mixing Ratio Calculator

Combine two solutions of known concentration to find the final concentration and total volume, or solve for the volume of B needed to dilute…

Molality Calculator

Compute molality (m, mol/kg) from solute mass or moles and solvent mass. Includes 10 preset substances and the inverse mass-needed mode.

Molar Mass Calculator

Compute molar mass from any chemical formula. Supports nested parentheses, like Ca(OH)2 and (NH4)2SO4. Returns total g/mol and percent by ma…

Molar Mass of a Gas Calculator

Compute the molar mass of a gas from its sample mass, pressure, volume, and temperature using the ideal gas law. R = 0.082057 L atm / (mol K…

Molar Ratio Calculator

Convert between moles of two substances using stoichiometric coefficients from a balanced equation, or reduce a ratio of mole values to its …

Mole Fraction Calculator

Compute mole fractions x_A and x_B of a two-component mixture. Input moles directly or compute them from mass and molar mass.

Molecular Weight Calculator

Compute molecular weight from any chemical formula. Includes optional mass/mole/particle conversion using Avogadro's constant.

Nernst Equation Calculator

Compute the non-standard cell potential E from E°, the number of electrons transferred n, the reaction quotient Q, and the temperature.

Neutralization Calculator

Solve titration problems with the M_a V_a = M_b V_b formula. Optional stoichiometric coefficients handle diprotic acids and dihydroxy bases.

Normality Calculator

Calculate normality (Eq/L) from mass, molarity, or run the titration dilution formula. Includes 10 preset acids and bases.

Osmotic Pressure Calculator

Calculate osmotic pressure (Π) of a solution using Π = iMRT. Inputs: molarity, temperature in Kelvin, and van't Hoff factor for electrolyte …

Percent Composition Calculator

Calculate the percent composition by mass of each element in a compound. Enter atomic masses and counts, or pick from 9 common compounds.

Percent Ionic Character Calculator

Estimate the percent ionic character of a bond from electronegativity difference. Pauling formula, classification by polarity, 38 element pr…

Percent Solution Calculator

Calculate solution concentration as mass percent (% w/w), weight/volume percent (% w/v), or volume percent (% v/v) with three working modes.

Percentage to Molarity Calculator

Convert solution mass percent (% w/w) to molarity using M = (10 × % × ρ) / Mᵣ. Built-in presets for common concentrated lab reagents.

Protein Solubility Calculator

Estimate protein solubility from pH, temperature, and ionic strength. Includes BSA, lysozyme, insulin, gamma globulin, and collagen.