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Physics formula

How to calculate density

Density tells how much mass is packed into a given volume.

See the formulaOpen calculator
Direct answer
Formula
rho = m / V

Use the table below to match each symbol with the right input. Keep units consistent before you start.

Density formula
Start here when you only need the equation and variable names.
Formula
rho = m / V

Density tells how much mass is packed into a given volume.

Variable meanings
Check each symbol, meaning, and unit before you calculate.
SymbolNameDescriptionUnit
rhoDensityMass per unit volume.kg/m^3
mMassAmount of matter.kg
VVolumeSpace occupied.m^3
When to use this formula
Check that your situation matches the formula before you trust the result.
  • Fits materials, liquids, gases, and buoyancy problems when mass and volume are known.
Step-by-step method
Follow these steps when you are solving it by hand.
  1. 1Convert mass to kilograms if using SI units.
  2. 2Convert volume to cubic meters.
  3. 3Divide mass by volume.
  4. 4Report density in kg/m^3 or another matching mass-per-volume unit.
Examples
These sample numbers show the order of operations and units.
Metal sample
m
10 kg
V
0.002 m^3
  1. 1.rho = 10 / 0.002
  2. 2.rho = 5000 kg/m^3
Result
The density is 5,000 kg/m^3.
Liquid sample
m
0.8 kg
V
0.001 m^3
  1. 1.rho = 0.8 / 0.001
  2. 2.rho = 800 kg/m^3
Result
The density is 800 kg/m^3.
Mistakes to avoid
Small input or unit errors can change the answer a lot.
  • Mixing metric and imperial units before solving the density formula.
  • Forgetting squared units such as m^2, m/s^2, or velocity squared.
  • Dropping negative signs when direction matters.
  • Rounding measured values too early in the calculation.
Open the Density Calculator
Open the calculator for the answer without rewriting the formula.

Enter your values in the related calculator, then compare the output with the hand method above.

Open Density Calculator
FAQs
Short answers for common formula questions.
Can I calculate Density by hand?

Yes. Write the units next to each value, convert rates or measurements first, and round only the final answer.

Why does my Density result differ from another calculator?

Most differences come from rounding, unit conversions, rate timing, or a slightly different version of the formula.

When is the Density Calculator better than hand math?

Open the Density Calculator to check several scenarios or skip the hand arithmetic.