Article — Maintenance Calorie Calculator
Maintenance calorie calculator: the daily intake that holds your weight
Maintenance calories are the energy intake at which your weight stays flat. The formula is BMR (Mifflin-St Jeor equation) multiplied by an activity factor between 1.2 and 1.9. A 30-year-old man at 82 kg and 178 cm with moderate activity needs about 2770 kcal per day. The same calculation for a 65 kg, 165 cm woman of the same age and activity comes out near 2090 kcal.
The number is not a constant. It drops with age, falls as you lose weight, and shifts when your routine changes. The calculator above and the reference tables below cover the math, the corrections, and the most common reasons real intake does not match the predicted figure.
What are maintenance calories?
Maintenance calories, also written TDEE (total daily energy expenditure), are the daily intake at which energy in equals energy out. Eat that number and your weight does not move over weeks. Eat above it and you gain; eat below it and you lose.
TDEE has four components: basal metabolism (60-70%), the thermic effect of food (about 10%), planned exercise (5-15%), and non-exercise activity thermogenesis or NEAT (15-30%). The Mifflin-St Jeor equation predicts the BMR component directly. The other three are bundled into the activity factor.
The Academy of Nutrition and Dietetics adopted Mifflin-St Jeor as the preferred BMR equation in 2005 after a systematic review of 25 studies. It outperformed Harris-Benedict, Owen, and the World Health Organization equation on accuracy and bias. It is now the equation used in most clinical and consumer calculators worldwide.
How the maintenance calorie calculator works
Two steps. First compute BMR from age, sex, height and weight. Then multiply by the activity factor.
men = 10W + 6.25H - 5A + 5women = 10W + 6.25H - 5A - 161W kg, H cm, A years BMR in kcal/dayExample for a 30-year-old man at 82 kg and 178 cm: BMR = 820 + 1112.5 - 150 + 5 = 1787.5 kcal. With moderate activity (factor 1.55), maintenance = 1787.5 × 1.55 = 2770 kcal per day.
The equation is empirical. Mifflin and colleagues derived it in 1990 from indirect calorimetry on 498 healthy adults aged 19-78. They published the constants in the American Journal of Clinical Nutrition. The coefficients are not arbitrary — they are the regression weights that minimized error against measured BMR.
Activity factors for maintenance calories
Activity factor scales BMR up to TDEE. Five levels cover the realistic range from desk-bound to professional athlete.
- 1.2 sedentary — desk job, no planned exercise, mostly seated
- 1.375 lightly active — 1-3 short sessions per week, daily walking
- 1.55 moderately active — 3-5 real workouts per week
- 1.725 active — 6-7 days of training or a physical job
- 1.9 very active — twice-daily training or heavy manual labor
- common error — picking moderate when sedentary is honest
- NEAT spread — non-exercise movement ranges 400-2000 kcal/day between individuals
Self-reported activity is consistently inflated. A 2010 NIH study found that office workers who described themselves as moderately active actually accumulated only about 25 minutes of moderate-intensity movement per day — well inside the lightly active band. If you sit at a desk and gym twice a week, the honest factor is 1.375, not 1.55.
Maintenance vs. cut vs. bulk
Three states sit around the maintenance number. A cut runs a daily deficit and produces weight loss. Maintenance holds the line. A bulk runs a surplus and supports muscle gain.
The 500-kcal deficit rule comes from Max Wishnofsky's 1958 calculation that 1 pound of body fat stores about 3500 kcal. Modern research has refined this — actual loss runs about 10-15% slower than the simple math predicts because the body adapts. But 500 kcal per day still produces roughly 1 lb per week for the first 4-8 weeks of a diet, and it remains the CDC's standard recommendation.
Macros on maintenance calories
Once you have a maintenance calorie number, splitting it into protein, carbs and fat gives a daily nutrition target. The calculator offers four presets.
Protein and carbohydrates each supply 4 kcal per gram. Fat supplies 9 kcal per gram. A 30% protein share of 2500 kcal equals 750 kcal ÷ 4 = 188 g of protein. A 50% fat share would be 1250 kcal ÷ 9 = 139 g of fat.
Set protein first, distribute the rest. Most evidence-based targets land between 1.6 and 2.2 g of protein per kg of body weight per day for active adults. Anchor that number, then split the remaining calories between carbs and fat according to preference. Endurance athletes lean carb-heavy; strength athletes often run moderate fat.
The USDA Dietary Guidelines define acceptable macronutrient distribution ranges (AMDR): protein 10-35%, carbs 45-65%, fat 20-35% of total energy. The four presets in this calculator all sit inside or at the edge of those ranges.
Why maintenance calories change
Your maintenance calorie number is not fixed for life. Four factors shift it over time.
- weight — every 5 kg lost drops maintenance about 100-150 kcal/day
- age — BMR falls 1-2% per decade after 30, mostly via muscle loss
- muscle — 1 kg of muscle burns ~13 kcal/day; 1 kg of fat ~5 kcal/day
- adaptation — chronic dieting can drop BMR 5-10% below predicted
- medications — beta-blockers, antidepressants, thyroid drugs shift BMR ±5-15%
- climate — cold environments raise daily energy use up to 10%
The first two are the biggest drivers. A 40-year-old who weighed 90 kg at 25 and now weighs 80 kg has lost two decades of metabolic mass. Their maintenance is roughly 300-400 kcal lower than it was at 25, not because anything broke but because the math is different.
Common maintenance calorie mistakes
Four errors account for most failed attempts to find the right intake.
Overestimating activity. The single biggest mistake. Two gym sessions a week plus a desk job is lightly active (1.375), not moderate. Real moderate activity is 3-5 hard sessions per week sustained over months.
Treating maintenance as static. Calculate once, eat that number forever, then wonder why the loss stalled or the bulk got messy. Recalculate every 4-6 weeks during a diet and every 6-12 months otherwise.
Trusting smartwatch calorie counts. A 2017 Stanford Medicine study found wrist-based devices overestimated calorie burn by 27-93%. Heart-rate readings were accurate; the calorie math layered on top was not. The MET-based and Mifflin-St Jeor approaches give more conservative, more reliable numbers.
Eyeballing portions. Self-reported intake underestimates real intake by 20-40% on average. If your numbers say you should lose and you are not losing, the gap is almost always in tracking accuracy, not metabolism.
How to verify your maintenance number
The calculator gives a prediction. To find your true maintenance, run a short experiment.
Eat the predicted number for 14 days. Weigh yourself daily at the same time and take the 7-day rolling average. If the average is flat across the two weeks, the prediction is correct. If the average drifts up by 0.5 kg, your real maintenance is about 250 kcal/day lower. If it drifts down, real maintenance is 250 kcal higher.
Two weeks is the minimum. Single-day weights vary by 1-2 kg from water, glycogen and digestion — useless signal. The 7-day moving average filters that noise out. A 14-day window captures one menstrual cycle phase for women, which matters because water retention varies by 0.5-1.5 kg across a cycle.
Indirect calorimetry — measuring BMR directly via oxygen consumption and CO₂ production under a metabolic cart — is the lab gold standard. A single session costs $100-300 and takes 30-45 minutes. It is offered at most university exercise physiology labs and some sports medicine clinics. For people who do not respond as predicted to standard equations (very lean, very obese, on metabolic medications) it is the only way to get a reliable number.