Calculate concrete density, weight, or volume from mass, dimensions, and concrete type with metric, imperial, and custom density units.
Concrete Density Formula
The calculator works from the basic density relationship and rearranges it for whichever value you need.
density = mass / volume weight = density * volume volume = mass / density
- density - mass per unit volume of the hardened concrete (kg/m³)
- mass - weight of the concrete sample or pour (kg)
- volume - space the concrete occupies (m³)
For rectangular shapes, volume = length × width × thickness. For a cylinder or core sample, volume = π × (diameter / 2)² × height. All inputs are converted to SI units before the calculation, so the unit you pick in each dropdown does not change the result. The figures assume fully consolidated concrete with no large voids.
Typical Concrete Densities
Use these ranges to sanity check a result or to pick a density when you only know the concrete type.
| Concrete type | Density (kg/m³) | Density (lb/ft³) |
|---|---|---|
| Aerated / foam concrete | 400 - 1,200 | 25 - 75 |
| Lightweight structural | 1,600 - 2,000 | 100 - 125 |
| Plain concrete | 2,200 - 2,400 | 137 - 150 |
| Normal-weight concrete | 2,300 - 2,500 | 144 - 156 |
| Reinforced concrete | 2,400 - 2,600 | 150 - 162 |
| Heavyweight (barite, magnetite) | 3,000 - 4,000 | 187 - 250 |
Common unit conversions used by the calculator:
| From | To | Multiply by |
|---|---|---|
| kg/m³ | lb/ft³ | 0.06243 |
| kg/m³ | g/cm³ | 0.001 |
| m³ | ft³ | 35.315 |
| m³ | yd³ | 1.308 |
| kg | lb | 2.2046 |
Worked Example and FAQ
Example. A core sample weighs 3.85 kg. Its diameter is 100 mm and its height is 200 mm.
- Volume = π × (0.05)² × 0.20 = 0.001571 m³
- Density = 3.85 / 0.001571 ≈ 2,451 kg/m³
That falls in the normal-weight range, so the sample looks consistent with a standard mix.
Why does my result look too low? Most low readings come from a unit mistake. Confirm the dimension unit matches the value you typed, and that mass is not in grams when the dropdown says kilograms.
Does reinforcement change the density? Yes. Steel rebar pushes the average density of reinforced sections to roughly 2,500 kg/m³ versus about 2,400 kg/m³ for plain concrete. Use the reinforced option when steel content is significant.
Fresh vs. hardened density. Fresh concrete is typically 30 to 80 kg/m³ heavier than the same mix once cured, because of evaporable water. The calculator gives the density of whatever sample you measure.
Which density should I use for weight estimates? Use 2,400 kg/m³ (150 lb/ft³) for most slab, footing, and wall pours unless the mix design states otherwise.
