Density Formula
The density formula connects mass, volume and density. This guide shows the three rearrangements, unit handling, dimensional analysis and worked examples so the equation remains useful outside a memorized triangle.
The density equation
ρ=m/VDensity equals mass divided by volume.
The three rearranged formulas
ρ=m/Vm=ρVV=m/ρChoose the rearrangement that leaves the unknown quantity by itself.
Dimensional analysis
Units should cancel to the desired output. For example, kg divided by m³ produces kg/m³. If mass is in grams and volume in mL, the result is g/mL. Convert before calculating when the units are not compatible.
Worked examples
Find density
500 g ÷ 200 cm³ = 2.5 g/cm³.
Find mass
7850 kg/m³ × 0.01 m³ = 78.5 kg.
Find volume
10 kg ÷ 1000 kg/m³ = 0.01 m³ = 10 L.
Average density
For a composite or hollow object, average density can be total mass divided by total external volume. This may differ greatly from the density of the solid material making up the object.
Frequently asked questions
What is the formula for density?
ρ=m/V.
How do I find mass from density?
m=ρV.
How do I find volume from density?
V=m/ρ.
Sources & references
We prefer standards bodies, government/scientific agencies and primary technical references. Reference values can vary with conditions, grade, composition or measurement method.
Related calculators & guides
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