Mass density is mass divided by occupied volume: ρ = m/V, with coherent SI unit kg/m³. It is not mass itself, and it is not weight, which is a force measured in newtons. Specific weight is weight per volume, γ = W/V = ρg, while bulk density uses a stated bulk volume that can include space between particles. DensityCalc calculates only mass density from entered mass and volume; it does not choose gravity, measurement conditions, identify a material, or certify a use.
Five related terms, five different questions
Mass m asks how much matter and uses kilograms. Volume V asks how much space and uses cubic metres. Mass density ρ asks mass per occupied volume and uses kg/m³; for example, 2 kg ÷ 0.001 m³ = 2000 kg/m³. Weight W is gravitational force in newtons and requires a stated acceleration. Specific weight γ is W/V in N/m³. Bulk density still divides mass by volume, but its declared bulk volume can include inter-particle voids, so it is not automatically the same measurement as the density of the solid material.
Mass and weight are different quantities
Mass is measured in kilograms. Weight is a force that depends on gravitational acceleration and is measured in newtons. Enter a measured mass, not a force reading that has not been converted by the instrument.
Use ρ for mass density and γ for specific weight
Mass density is ρ = m/V and its coherent SI unit is kg/m³. Specific weight is a different quantity: γ = W/V = ρg, expressed in N/m³. Symbols can vary by source, so define them; DensityCalc does not calculate γ or choose a gravity value, and this distinction is not a structural or load calculation.
Bulk density includes the chosen occupied space
Powders, grains, and porous materials may include voids between particles in the measured volume. Packing, moisture, and procedure can change that result, so the calculator never substitutes a reference value or labels a material.
State temperature and pressure when they matter
Fluid density can vary with temperature and pressure. DensityCalc records neither condition and offers no authoritative material table, so preserve them separately whenever the result supports scientific or engineering work.