Physics Tools
What It Does
Works out density, mass, or volume from the other two using ρ = m / V, in whatever units suit you (kg/m³ or g/cm³; kg/g/mg; m³/L/mL/cm³), with material presets and a “will it float?” check. Everything runs in your browser.
How to Use It
- Choose what to solve for (density, mass, or volume).
- Enter the other two values and pick their units — or choose a material to fill the density for you.
- Read the result (density is also shown in g/cm³); the working is shown below it.
- Click Copy on the result to grab the raw value.
About Density
Density is how much mass is packed into a given volume — ρ = m / V — and it is what decides whether something floats or sinks. Because the three quantities are locked together by one equation, knowing any two always gives you the third: weigh a sample and measure its volume to get its density, or use a known density to turn a volume into a mass. Density is usually quoted in kilograms per cubic metre (kg/m³) in SI or grams per cubic centimetre (g/cm³) in the lab — and the two differ by exactly a factor of 1000, so water is both 1000 kg/m³ and 1 g/cm³. Water is the natural yardstick: by Archimedes’ principle, an object floats when its average density is less than the fluid around it, so ice (slightly less dense than liquid water) floats while iron and gold sink. That same idea explains why a steel ship floats — its average density, hull plus the air inside, is lower than water’s even though steel itself is far denser. The material presets here use standard reference densities at everyday conditions; real samples vary with temperature, pressure, purity, and (for gases) a great deal. Everything is computed on your device.
Example
Solve for density, m = 2 kg, V = 0.001 m³ → ρ = 2000 kg/m³ (= 2 g/cm³).
Frequently Asked Questions
What’s the difference between g/cm³ and kg/m³?
They measure the same thing in different scales: one gram per cubic centimetre equals exactly 1000 kilograms per cubic metre. Water is 1 g/cm³ or 1000 kg/m³. This tool shows density in both so you can use whichever your problem expects.
Will my object float in water?
Compare its average density to water’s (1000 kg/m³). Less dense → it floats; the same → it is neutrally buoyant; denser → it sinks. The result panel shows this note automatically once you have a density.
Where do the material values come from?
The presets are standard reference densities at everyday conditions (room temperature, atmospheric pressure). Real samples vary with temperature, pressure, alloying, and purity, so treat them as typical values rather than exact ones — especially for gases like air.
Can I solve for mass or volume too?
Yes. Pick what to solve for at the top: enter any two of density, mass, and volume and the tool computes the third with ρ = m/V, m = ρ·V, or V = m/ρ.
Is my data sent to a server?
No. Every calculation runs locally in your browser; nothing you enter is transmitted or stored.