Density Calculator · Practical guide
How to Find Density from Mass and Volume
Density equals mass divided by volume — weigh it, measure it, divide, and the calculator handles the unit conversions.
At a glance
Quick answer
To find density, divide the object's mass by its volume: D = M / V. A 500-gram rock that displaces 200 cm³ of water has a density of 500 / 200 = 2.5 g/cm³, which equals 2,500 kg/m³ or about 156.1 lb/ft³.
Interactive tool
Density Calculator
Enter your own values, then compare the result with the examples below.
Results
The Formula
The relationship is a single equation with three variables: Density = Mass / Volume. Enter any two above and the third is solved automatically. The result is always shown in all three common unit systems, so no separate conversion step is needed.
Worked Example: Identifying a Metal
Suppose a mystery block of metal has a mass of 540 grams and a volume of 200 cm³. Its density is 540 / 200 = 2.7 g/cm³. Comparing against known values — aluminum is 2.70 g/cm³, iron 7.87, gold 19.32 — the block is almost certainly aluminum.
Getting the Measurements Right
- Measure mass with a scale in grams or kilograms.
- For regular solids, compute volume from dimensions; for irregular ones, use water displacement.
- Keep units consistent: grams with cm³, or kilograms with m³.
Why Density Is Useful
Density stays constant for a pure material regardless of size, which makes it a fingerprint for identifying substances, checking whether something will float (anything under 1 g/cm³ floats in water), and estimating shipping weight from dimensions alone.
Frequently Asked Questions
What units should I use for mass and volume?
Any consistent pair works. Grams and cubic centimeters give g/cm3 directly; kilograms and cubic meters give kg/m3. The calculator displays the answer in both, plus lb/ft3.
How do I measure the volume of an irregular object?
Use water displacement: submerge the object in a graduated container and note the rise in water level. The rise in milliliters equals the volume in cubic centimeters.
Does density tell me if something will float?
Yes. Water has a density of 1 g/cm3 (1000 kg/m3), so anything less dense floats and anything denser sinks.
Why does the calculator need exactly two values?
Density, mass, and volume are linked by one equation, so any two determine the third. With only one value there are infinitely many possible answers.