Concrete weight formula
weight (lb) = volume (ft³) × density (lb/ft³)
short tons = lb ÷ 2,000
kg = lb × 0.45359
lb per yd³ = density × 27
Worked example: 10 × 10 ft slab, 4 in thick
- Volume: 10 × 10 × (4 ÷ 12) = 33.33 ft³.
- Weight: 33.33 × 150 = 5,000 lb.
- Tons: 5,000 ÷ 2,000 = 2.5 short tons.
- Kilograms: 5,000 × 0.45359 = 2,268 kg.
How much does concrete weigh?
At the default of 150 lb/ft³ :
| Volume | Pounds | Short tons | Kilograms |
|---|---|---|---|
| 1 ft³ | 150 | 0.07 | 68 |
| 1 yd³ | 4,050 | 2.02 | 1,837 |
| 10 × 10 ft slab, 4 in | 5,000 | 2.50 | 2,268 |
| 12 in tube, 4 ft tall | 471 | 0.24 | 214 |
| 8 × 8 ft pad, 6 in | 4,800 | 2.40 | 2,177 |
| 1 m³ | 5,297 | 2.65 | 2,403 |
Why the density is an assumption
Concrete weight depends on the aggregate, air content, and moisture. 150 lb/ft³ (4,050 lb/yd³) is a common planning number. Concrete Network cites about 4,000 lb/yd³. Neither is a lab measurement of your mix, so the field is editable . Lightweight concrete made with expanded shale or similar aggregate is much lighter.
Where weight matters
- Hauling and disposal. Trailers and dumpsters have weight limits. Breaking out an old slab? Estimate it here first.
- Bags in the truck. 45 bags of 80 lb mix is 3,600 lb. The concrete bag calculator gives the count.
- Elevated pours. Formwork and decks must carry wet concrete. That is an engineering check, not a calculator one.
Need the volume first? The concrete calculator handles every shape and also shows weight.