Concrete Weight Calculator
Calculate how much a concrete slab weighs: enter length, width, and thickness to get the weight in pounds and tons at 150 lb per cubic foot.
How this calculator works
A concrete slab is a rectangular block, so its volume is length times width times thickness. Once you know the volume in cubic feet, you multiply by concrete’s density to get the weight. Normal concrete weighs about 150 pounds per cubic foot, so a bigger or thicker slab climbs in weight fast.
Thickness is usually given in inches, so it gets converted to feet first by dividing by twelve. That keeps all three dimensions in feet, giving a volume in cubic feet that lines up with the 150 lb per cubic foot density.
Formula: Volume (cu ft) = length × width × thickness-in-feet; Weight = volume × density (about 150 lb per cubic foot).
Worked example
A 10 ft × 10 ft slab, 4 in thick:
- Thickness in feet: 4 ÷ 12 ≈ 0.333 ft
- Volume: 10 × 10 × 0.333 = 33.33 cu ft
- Weight: 33.33 × 150 ≈ 5,000 lb
- That is 2.5 tons, or ≈1.23 cu yd of concrete
Reference
Concrete weight (150 lb/ft³):
| Volume | Weight |
|---|---|
| 1 cubic foot | 150 lb |
| 1 cubic yard (27 ft³) | 4,050 lb (2.03 tons) |
How to use
Enter the slab’s length and width in feet and its thickness in inches, and read off the weight in both pounds and tons. Use this to gauge what the ground or supporting structure carries and to plan hauling, keeping in mind that lightweight or heavy-aggregate mixes shift the density.
Weights are estimates based on typical densities. Actual weight varies with moisture, mix design, and material grade — confirm with your supplier.
Frequently asked questions
Why is 150 pounds per cubic foot used for concrete?
Normal-weight concrete made with standard sand and stone aggregate weighs about 150 pounds for every cubic foot. This is a widely used planning figure for slabs, footings, and walls. Lightweight mixes weigh less and heavy aggregate mixes weigh more, so treat 150 as a solid default rather than an exact value for every mix.
How do I turn slab thickness in inches into feet?
Divide the thickness in inches by twelve, since there are twelve inches in a foot. A four-inch slab is four divided by twelve, which is about 0.333 ft. Using thickness in feet keeps every dimension in the same unit, so length times width times thickness gives you a clean cubic-foot volume.
Why does a slab's weight matter?
Weight tells you what the ground, forms, or supporting structure has to carry, and it hints at how much material a delivery truck is hauling. For anything raised off the ground or spanning between supports, knowing the load in pounds and tons is a starting point for planning. Structural support decisions still need a qualified engineer.
How do pounds convert to tons here?
A US ton is two thousand pounds, so divide the weight in pounds by two thousand to get tons. A slab weighing five thousand pounds is five thousand divided by two thousand, which is 2.5 tons. Tons are handy for talking to suppliers and haulers who quote loads in tons rather than pounds.
Estimates only. Verify quantities with your supplier before purchasing.