Article — Concrete Weight Calculator
Concrete Weight Calculator: Pounds, Tons, and Metric Equivalents
A cubic yard of normal-weight concrete weighs about 4,050 lb (2.0 short tons or 1.84 metric tons). The standard density is 150 lb/ft³ or 2,400 kg/m³, codified in ACI 318 (Building Code Requirements for Structural Concrete). Lightweight concrete drops to 90-120 lb/ft³, and reinforced concrete with 1% steel rises to about 152 lb/ft³. The exact weight depends on aggregate type, water content, and any admixtures.
Concrete weight matters for foundation design, truck dispatch, floor-load ratings, and disposal of demolition debris. A ready-mix truck typically carries 8-10 cubic yards, which weighs 30,000-40,000 lb — close to the legal maximum for a fully loaded mixer in most US states.
How much does concrete weigh
For normal-weight concrete, the answer is 150 pounds per cubic foot or about 2,400 kilograms per cubic meter. Multiply that figure by your volume to get total weight: a 10 ft × 10 ft × 4 in slab contains 33 ft³ of concrete and weighs roughly 5,000 lb. A standard residential driveway (20 ft × 30 ft × 4 in) holds about 200 ft³ and weighs 30,000 lb, the same as a small fire truck.
Round numbers worth memorizing: 1 yd³ = 4,050 lb (2 short tons), 1 m³ = 2,400 kg (2.4 metric tons), 1 80-lb bag yields 0.60 ft³ and so weighs almost exactly 80 lb after mixing (the added water is roughly offset by air voids).
Concrete is the second-most-consumed material on Earth after water — humanity pours about 30 billion tonnes per year. The Hoover Dam alone contains 3.25 million yd³ (~6.6 million tons) of concrete, enough to pave a 16-foot-wide highway from San Francisco to New York.
Concrete weight formula
Concrete weight is volume times density. The unit selection is where most mistakes happen, because slabs are specified in cubic yards in the US, cubic meters in metric markets, and individual mix bags in pounds.
1 ft³ normal 150 lb1 yd³ normal 4,050 lb / 2 tons1 m³ normal 2,400 kg / 2.4 t1 yd³ 0.7646 m³1 lb/ft³ 16.0185 kg/m³The base formula: W = V × ρ, where V is volume and ρ is density. For normal-weight concrete in US customary units: W (lb) = V (ft³) × 150. To convert to short tons divide by 2,000; to convert to kilograms multiply lb by 0.4536.
Concrete density by mix type
Density varies with aggregate. Normal-weight concrete uses crushed limestone or gravel and weighs 140-150 lb/ft³. Lightweight concrete substitutes expanded shale, clay, or pumice and drops to 90-120 lb/ft³ — used for upper-floor slabs to reduce dead load. Reinforced concrete (with 1-2% steel rebar by volume) gains 2-4 lb/ft³. Heavyweight concrete uses magnetite or hematite aggregate for nuclear shielding and reaches 240-380 lb/ft³.
Concrete weight by volume
For common project sizes, the weight figures are predictable. A 4-inch sidewalk slab weighs ~50 lb per square foot. A 4-inch driveway slab covering 600 ft² weighs 30,000 lb (200 ft³ × 150 lb/ft³), or about 7.5 cubic yards. A small foundation footing of 2 ft × 1 ft × 100 ft holds 200 ft³ and likewise weighs 30,000 lb.
- 1 yd³ = 4,050 lb (2.0 short tons, 1.84 metric tons)
- 1 m³ = 5,290 lb (2,400 kg, 2.4 metric tons)
- 4 in slab = 50 lb / ft² for normal concrete
- 6 in slab = 75 lb / ft²
- 80-lb bag yields 0.60 ft³ (60 bags = 1 yd³)
- Full mixer truck (10 yd³) carries ~40,500 lb of concrete
Wet vs. dry concrete weight
Freshly poured concrete contains 15-20% water by weight. As it cures over 28 days, some water bonds chemically into calcium silicate hydrate gel; the rest evaporates. Net weight loss over the first 90 days is 5-10% for typical mixes. A 4,050-lb cubic yard of fresh concrete weighs about 3,800 lb after a year of drying in normal indoor conditions.
The "80 lb" stamped on a bag refers to the dry mix only. When you add water and mix, the resulting concrete weighs more — about 90 lb per 80-lb bag after mixing with the recommended 6 pints of water. Order trucks and trailers by the cured weight of concrete, not the bag weight on the label.
Load and truck capacity planning
Concrete weight drives delivery logistics. A standard ready-mix truck has a 10 yd³ drum capacity, but most loads are limited to 8-9 yd³ to stay under the 80,000-lb federal gross-vehicle-weight limit when accounting for the truck itself (~30,000 lb empty). Always confirm with your supplier on short-load fees: orders under 3 yd³ typically incur $80-$150 in extra charges to cover the wasted truck capacity.
A 6-foot utility trailer rated for 3,500 lb can carry about 0.85 yd³ of concrete safely. Calculate your trailer's payload from its GVWR minus tare weight before hauling any concrete, demolition debris, or rebar.
Common concrete weight mistakes
Three errors recur in concrete weight estimates. Confusing cubic feet and cubic yards is the most common — there are 27 ft³ in 1 yd³, not 3. Using "tons" without specifying short (2,000 lb) or metric (1,000 kg) creates a 10% error in cross-unit calculations. Forgetting that lightweight concrete is 25-40% lighter than normal-weight can cause foundations to be over- or under-engineered.
A fourth pitfall: ignoring rebar weight when planning demolition. A heavily reinforced slab can be 3-5% heavier than its concrete alone, and the steel itself sells as scrap metal during cleanup. For a 30-ton driveway demolition, the embedded rebar might weigh 1,200-1,500 lb. Subtract this from concrete-disposal estimates if the demolition contractor separates and recycles steel.
Concrete weight reference data
For quick mental math: divide US customary lb/ft³ by 16 to approximate metric tonnes per cubic meter. So normal concrete at 150 lb/ft³ is about 2.4 t/m³, lightweight at 110 lb/ft³ is 1.76 t/m³, and heavyweight shielding concrete at 240 lb/ft³ is 3.85 t/m³. These figures align with ASTM C138 (Standard Test Method for Unit Weight of Concrete), the field test used to verify mix density on a pour.