1,000 kg/m³ equals about
9,81 kN/m³
This is the inverse operation compared to the kN/m³ → kg/m³ conversion. Knowing a material's density (mass per unit of volume), you can calculate its specific weight (weight-force per unit of volume) by multiplying by the standard acceleration of gravity, following the same logic as Newton's second law applied per unit of volume.
To convert from kg/m³ to kN/m³, multiply by 9.80665 and divide by 1,000:
To convert from kN/m³ to kg/m³, perform the inverse operation:
This conversion is essential in structural and geotechnical calculations, where starting from a material's density (often easier to find or measure) you need to calculate the specific weight required for foundation design formulas, retaining walls, or other structures subject to gravitational loads.