Concrete weight calculator: how much does my concrete weigh?
4,833 lb
2.42 short tons · 33.3 cu ft (1.23 cubic yards) at 145 lb per cu ft, 1.96 tons per cubic yard · for a 10 × 10 ft slab 4 in thick at 145 lb per cu ft
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4,833 lb
2.42 short tons · 33.3 cu ft (1.23 cubic yards) at 145 lb per cu ft, 1.96 tons per cubic yard
Source: WSDOT Bridge Design Manual M 23-50.24, Table 3.8-1 Permanent Loads, design unit weights of concrete, read October 16, 2026. Data sheet (PDF)
A 10 by 10 ft concrete slab 4 inches thick weighs about 4,833 lb, 2.42 short tons, at 145 lb per cubic foot, the design weight the Washington State DOT uses for plain concrete; reinforced concrete is figured at 155.
A worked example
A reinforced landing pad 7 ft 8 in by 3 ft 4 in and 5 1/2 in thick needs 1,816 lb. 7.67 × 3.33 ft × 5.5/12 ft is 11.71 cubic feet. At 155 lb per cubic foot for reinforced concrete that is 1,816 lb, 0.91 short tons.
How much does concrete weigh per cubic foot?
The Washington State DOT Bridge Design Manual figures plain concrete at 145 lb per cubic foot and normal-weight reinforced concrete at 155 lb, 5 lb of which is the steel. Lightweight concrete is 110 to 135 lb per cubic foot depending on the mix. These are the design weights engineers use to compute loads, which is why the calculator lets you pick one instead of fixing a single number.
How much does a cubic yard of concrete weigh?
A cubic yard is 27 cubic feet, so at 145 lb per cubic foot it is 3,915 lb, 1.96 short tons, and reinforced at 155 lb it is 4,185 lb, 2.09 tons. Lightweight concrete at 110 to 135 lb per cubic foot is 2,970 to 3,645 lb a yard. Multiply by the yards in your pour to get the weight a truck or a trailer carries.
What else it is called
The weight of concrete is also called its unit weight or density, written in pounds per cubic foot (pcf). Concrete block is a different product whose weight depends on the block, so it is not on this page. For the bags or cubic yards to pour, the concrete slab calculator does that count.
Slab weights
| Slab | 4 in | 5 in | 6 in | 8 in |
|---|---|---|---|---|
| 8 × 8 ft | 3,093 | 3,867 | 4,640 | 6,187 |
| 10 × 10 ft | 4,833 | 6,042 | 7,250 | 9,667 |
| 10 × 12 ft | 5,800 | 7,250 | 8,700 | 11,600 |
| 12 × 12 ft | 6,960 | 8,700 | 10,440 | 13,920 |
| 12 × 16 ft | 9,280 | 11,600 | 13,920 | 18,560 |
| 16 × 20 ft | 15,467 | 19,333 | 23,200 | 30,933 |
| 20 × 20 ft | 19,333 | 24,167 | 29,000 | 38,667 |
Pounds of plain concrete at 145 lb per cubic foot. Reinforced concrete at 155 lb per cubic foot weighs 155/145 as much, about 7% more.
Where the numbers come from
- Unit weights: Washington State Department of Transportation, Bridge Design Manual (LRFD) M 23-50.24, June 2025, Chapter 3, Table 3.8-1 Permanent Loads. Unreinforced concrete 145 lb per cubic foot; normal-weight reinforced concrete 155 lb per cubic foot, which includes a 5 lb per cubic foot allowance for the reinforcement; lightweight or specified density concrete 110 to 135 lb per cubic foot. These are the design unit weights used to compute loads. Read October 16, 2026. WSDOT Bridge Design Manual, Chapter 3 (PDF)
- Volume is geometry: length × width × thickness in feet. Pounds are cubic feet × the unit weight you pick; short tons are pounds ÷ 2,000. Tons per cubic yard are the same unit weight × 27 ÷ 2,000: 1.96 for 145 lb and 2.09 for 155 lb.
The weight is the volume times a unit weight, so measure the thickness where it really is: a slab poured over a low spot is thicker there than at its forms. To weigh a slab you plan to break out and haul, measure it before breaking it; the broken pieces take more room with the air between them, but weigh the same.
By Javier Miralles · Last updated . How this site is made.
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