What this converter does
This density converter turns kilograms per cubic metre into pounds per cubic foot and back instantly. It handles the units used across construction and geotechnical work — g/cm³, t/m³, kN/m³ and lb/in³ — each with an exact ratio, so results are precise. Type a value and read the answer.
Density (or unit weight) drives concrete mix design, soil and steel calculations, and material takeoffs. For structural stress instead of density, see the MPa to psi converter.
The units it covers
Every unit here is a mass per unit volume, so each converts through the kilogram per cubic metre with a fixed ratio.
View all units & their values
| Unit | Symbol | Value | Mainly used |
|---|---|---|---|
| Kilogram per cubic metre | kg/m³ | 1 | SI density — concrete, soil, steel |
| Pound per cubic foot | lb/ft³ | 16.018 | US construction densities |
| Gram per cubic centimetre | g/cm³ | 1000 | Lab values, specific gravity |
| Tonne per cubic metre | t/m³ | 1000 | Bulk materials, aggregates |
| Kilonewton per cubic metre | kN/m³ | 101.97 | Unit weight in geotech design |
| Pound per cubic inch | lb/in³ | 27679.9 | Metals, dense materials |
The formula
Each unit has a fixed value in kg/m³, so converting between any two means passing through that base once:
result = value × factor_from ÷ factor_toWhere:
- value = the number you typed, in the “from” unit
- factor_from = the “from” unit’s value in kg/m³
- factor_to = the “to” unit’s value in kg/m³
Worked example
Convert 2400 kg/m³ (normal-weight concrete) to lb/ft³.
1 lb/ft³ = 16.018463 kg/m³2400 ÷ 16.018463 = 149.83 lb/ft³So 2400 kg/m³ concrete weighs about 150 lb/ft³.
The units in this example
The SI unit of density — mass in kilograms per cubic metre. Standard for concrete, soil and material densities across most of the world.
- 1 kg/m³ = 0.0624 lb/ft³
- 1000 kg/m³ = 1 g/cm³
- 1000 kg/m³ = 1 t/m³
- Water ≈ 1000 kg/m³
The US customary density unit — pounds of mass per cubic foot. Common in American construction specs and material data sheets.
- 1 lb/ft³ = 16.018 kg/m³
- Water ≈ 62.4 lb/ft³
- Concrete ≈ 150 lb/ft³
- Steel ≈ 490 lb/ft³