What to measure
How to use the concrete weight calculator
- Pick a rectangle or circle and enter its size.
- Enter the thickness of a slab, or the height of a column or footing.
- Keep 145 lb per cubic foot for ordinary concrete, or enter 115 for lightweight concrete or your supplier’s figure.
The formula
- Volume (cu ft) = length × width × thickness, all in feet (π × (diameter ÷ 2)² × height for a circle)
- Weight (lb) = volume × density
- Tons = pounds ÷ 2,000; kilograms = pounds × 0.4536
Worked example: 10 × 10 ft slab, 4 in thick
- Volume: 10 × 10 × (4 ÷ 12) = 33.33 cu ft (1.23 cu yd)
- Weight: 33.33 × 145 = 4,833 lb = 2.42 tons (2,192 kg)
- Load: 4,833 ÷ 100 sq ft = 48.3 lb per sq ft
Slab weight per square foot
| Thickness | Normal weight (145) | Lightweight (115) |
|---|---|---|
| 3 in | 36.2 lb | 28.8 lb |
| 4 in | 48.3 lb | 38.3 lb |
| 5 in | 60.4 lb | 47.9 lb |
| 6 in | 72.5 lb | 57.5 lb |
| 8 in | 96.7 lb | 76.7 lb |
Frequently asked questions
How much does a cubic yard of concrete weigh?
About 3,915 lb (just under 2 tons) for normal-weight concrete at 145 lb per cubic foot, and about 3,105 lb for lightweight concrete at 115 lb per cubic foot.
How much does a 10 × 10 concrete slab weigh?
At 4 inches thick, 33.3 cu ft of concrete weighs about 4,833 lb, or 2.42 tons. At 6 inches it's about 7,250 lb.
How much does concrete weigh per square foot?
About 48 lb per sq ft for a 4 in slab, 60 lb for 5 in and 72.5 lb for 6 in, using 145 lb per cubic foot. Multiply by the slab's area for its total weight.
How much does a sidewalk square weigh?
A 4 × 4 ft square, 4 in thick, is 5.3 cu ft of concrete, about 773 lb. That's why broken slabs are cut into smaller pieces before they're carried off.
Does rebar change the weight?
A little. Steel is about three times as heavy as concrete, so a heavily reinforced slab weighs a few percent more. Enter a higher density if your engineer gives one.
What is concrete's density in metric units?
145 lb per cubic foot is about 2,323 kg per cubic meter. Enter lengths in meters or centimeters and the calculator gives the weight in kilograms too.
How much does concrete weigh per cubic foot?
About 145 lb for normal-weight concrete and 115 lb for lightweight concrete, the defaults this calculator uses.
Sources
Formulas and defaults last reviewed October 30, 2026. How we check our math.