How this calculator works
The volume of the slab is its length times its width times its thickness in feet. Multiply by the weight of a cubic foot of concrete, 150 lb for normal concrete, to get the weight in pounds, and divide by 2,000 for US tons. Each inch of thickness adds 12.5 pounds per square foot.
Worked example: a 10 × 10 ft slab 4 inches thick is 33.3 cubic feet (1.23 cubic yards) and weighs 5,000 lb, or 2.50 tons (2,268 kg): 50.0 lb per square foot. At 6 inches it weighs 7,500 lb.
Weight of a concrete slab by thickness (normal concrete)
Per square foot, and for a 10 × 10 ft slab.
| Thickness | Pounds per ft² | Weight of 10 × 10 ft | Tons |
|---|---|---|---|
| 2 in | 25.0 | 2,500 lb | 1.25 |
| 3 in | 37.5 | 3,750 lb | 1.88 |
| 4 in | 50.0 | 5,000 lb | 2.50 |
| 5 in | 62.5 | 6,250 lb | 3.13 |
| 6 in | 75.0 | 7,500 lb | 3.75 |
| 8 in | 100.0 | 10,000 lb | 5.00 |
Tips before you buy
- Remember that concrete is heavy: a cubic yard weighs about 2 tons, and a ready-mix truck carries around 10 cubic yards.
- Do not put a heavy slab on a deck, balcony or roof without an engineer's check.
- Moving a precast piece takes equipment: plan the lifting, and know the weight before you order.
- The ground also has a limit. Soft soil under a heavy slab needs a thicker gravel base or a wider footing.
- Use the concrete calculator for the volume you need to order, with waste.
Tools & materials for this project
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Frequently asked questions
How much does a cubic yard of concrete weigh?
About 4,050 pounds (2 tons) for normal concrete at 150 lb per cubic foot.
How much does a 4 inch concrete slab weigh per square foot?
About 50.0 pounds per square foot: 12.5 lb for every inch of thickness.
How much does a 10x10 slab weigh?
5,000 lb (2.50 tons) at 4 inches thick, and 7,500 lb at 6 inches.
How much does a bag of concrete weigh once mixed?
An 80 lb bag makes about 0.6 cubic feet, which weighs about 90 lb once water is added and it is poured.
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Related calculators & guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.