Cube Density Calculator — Density from Mass and Side Length
Enter the mass of a cube and the length of one side to calculate its density in g/cm³, kg/m³ and lb/ft³. Supports metric and imperial units.
g
Mass unit
cm
Length unit
Density = mass ÷ volume = mass ÷ side³
4 g/cm³
Density- 1
Volume of cube (m³)
0.05³ = 0.000125 - 2
Density (kg/m³)
0.5 ÷ 0.000125 = 4,000 - 3
Density (g/cm³)
4,000 ÷ 1000 = 41 g/cm³ = 1 000 kg/m³, so dividing by 1 000 converts the units.
How does this calculator work?
For a cube, density = mass ÷ side³. Convert mass to kg and side to metres, then ρ (kg/m³) = mass (kg) / (side (m))³; divide by 1000 to get g/cm³. Enter mass, the side length and your units — the calculator handles all conversions.
Formula
How this is calculated
Density is defined as mass per unit volume: ρ = m / V. For a perfect cube all three edges are equal, so the volume is simply the edge length cubed: V = a³. The calculator converts every input to SI base units (kilograms and metres) before computing, so you can freely mix units — grams with centimetres, pounds with inches, and so on — and the result is always correct.
Once the density is known in kg/m³ the calculator derives two common alternative expressions: g/cm³ (divide by 1000 — numerically equal to the density in g/mL or kg/L), and lb/ft³ (multiply by 0.0624). Many material property tables list densities in g/cm³, where the reference point is water at 1.000 g/cm³; objects with density below 1 g/cm³ float in water.
The cube assumption is exact — real objects are never perfect cubes, so measure all three dimensions and use a cuboid formula if they differ. The formula also assumes uniform density throughout; composite or hollow objects need different methods.
Frequently asked questions
1 g/cm³ = 1000 kg/m³. So the same material measured in g/cm³ gives a number 1000 times smaller than in kg/m³. For example, water is 1.00 g/cm³ = 1000 kg/m³.
For any shape, density = mass / volume. This calculator computes volume as side³ (perfect cube). If the object is a rectangular cuboid, use length × width × height instead of side³ — the density formula itself is the same.
Fresh water has a density of 1.00 g/cm³ (1000 kg/m³). Any solid with density below 1.00 g/cm³ floats in fresh water; above 1.00 g/cm³ it sinks. Seawater is denser (~1.025 g/cm³), so the threshold shifts slightly.
TG we-Calculate Editorial Team. (2026). Cube Density Calculator — Density from Mass and Side Length [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/cube-density-calculator
TG we-Calculate Editorial Team. "Cube Density Calculator — Density from Mass and Side Length." TG we-Calculate. 2026. https://we-calculate.com/calculator/cube-density-calculator.
TG we-Calculate Editorial Team, "Cube Density Calculator — Density from Mass and Side Length," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/cube-density-calculator
@misc{wecalculate_cube_density_calculator, title = {Cube Density Calculator — Density from Mass and Side Length}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/cube-density-calculator}}, year = {2026}, note = {TG we-Calculate} }
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