Concrete weighs about 150 lb per cubic foot, so the weight is the volume in cubic feet times 150: a 10 ft by 10 ft slab 4 in thick is 33.3 cubic feet and weighs 5,000 lb, which is 2.5 tons or 2,268 kg.
How to calculate the weight of concrete
Weight (lb) = volume (cu ft) × 150 lb per cu ft 1 cubic yard = 27 cu ft = 4,050 lb
Choose a slab or block (length, width, thickness), a cylinder (diameter and height) or a plain volume in cubic yards, and the calculator finds the volume, multiplies by the density and prints pounds, tons and kilograms. Use "how many" for several identical pieces, like eight footings. The 150 lb per cubic foot figure is the concrete value in the Penn State fact sheet H-20; the calculator converts to kg per cubic meter (2,403) for the metric view.
Concrete weight per cubic foot and per cubic yard
One cubic foot of concrete weighs 150 lb, one cubic yard 4,050 lb (2.03 tons), and one cubic meter about 2,403 kg. Bagged mix labelled by the manufacturer is a little lighter: the Quikrete Concrete Mix data sheet gives a unit weight of about 140 lb per cubic foot, so a yard of it weighs about 3,780 lb. An 80 lb bag makes 0.60 cubic feet, which means 45 bags for a cubic yard and 3,600 lb of dry bags; the concrete bag calculator does the bag count.
Weight of a concrete slab
A slab weighs 50 lb per square foot at 4 in thick and 75 lb at 6 in. Multiply by the area:
| Slab thickness | Weight per sq ft | 10 x 10 ft slab | Volume of that slab |
|---|---|---|---|
| 4 in | 50 lb | 5,000 lb | 1.23 cu yd |
| 6 in | 75 lb | 7,500 lb | 1.85 cu yd |
| 8 in | 100 lb | 10,000 lb | 2.47 cu yd |
To order the concrete rather than weigh it, use the concrete slab calculator or the concrete yard calculator.
Weight of a concrete cylinder or column
A 12 in diameter post footing 3 ft deep is π ÷ 4 × 1 ft² × 3 ft = 2.36 cubic feet, so it weighs 353 lb. An 8 in tube 8 ft tall holds 2.79 cubic feet and weighs 419 lb. The sonotube concrete calculator gives the bags and yards for round forms.
Weight of broken concrete
Concrete demolished into pieces leaves gaps between the pieces. The EPA volume-to-weight table gives 860 lb per cubic yard of broken concrete, so a cubic yard of solid slab (4,050 lb) becomes about 4.7 yards of rubble. A 10 yard dumpster of loose broken concrete weighs about 8,600 lb, 4.3 tons, though dense pieces packed tightly weigh far more. Ask the hauler for the weight limit.
Truck and trailer payload
A truck's payload is its GVWR minus its curb weight (Knapheide), and it has to cover the load, the passengers and the tools. A pickup with a 2,000 lb payload carries 0.49 cubic yards of finished concrete, or 25 bags of 80 lb, which make 15 cubic feet (0.56 cubic yards) once mixed. That is why ready-mix arrives in a truck built for it. The calculator compares your weight with a payload you enter and counts the trips. On the road, federal limits on the Interstate are 80,000 lb gross, 20,000 lb per single axle and 34,000 lb on a tandem axle (23 CFR 658.17).
Rebar and wet concrete
Wet concrete in the truck weighs about the same as cured concrete, and a slab with steel in it is normally still taken at 150 lb per cubic foot. To weigh the reinforcement separately, use the steel weight calculator or count the bars with the rebar calculator.
Related calculators
For other materials by the cubic yard, use the cubic yards to tons calculator. More weight and volume tools are listed under measuring and planning calculators.