Density Calculator

Density, mass or volume, and whether it floats.

Density, mass or volume, and whether it floats. Density is mass over volume.

Written and maintained by Mohit PatelLast checked August 4, 2026How we build these

Solve for

Mass

Volume

m³

Density (kg/m³)

1,000

1 g/cm³ · neutrally buoyant in water

Density1,000 kg/m³

In g/cm³1

In lb/ft³62.428

Mass1,000 kg

Volume1 m³

Specific gravity1

In waterNeutrally buoyant

At exactly the density of water this is neutrally buoyant. It neither rises nor sinks, but hangs wherever it is placed, which is the state divers trim for. Density is mass over volume. Water is 1,000 kg/m³ — exactly 1 g/cm³, which is how the gram was originally defined — so specific gravity is just density in those units, and anything below 1 floats. That is the only comparison most density questions actually need.

How the Density Calculator works

Density is mass over volume. Water is 1,000 kg/m³ — exactly 1 g/cm³, which is how the gram was originally defined — so specific gravity is just density in those units, and anything below 1 floats. That comparison is what most density questions actually need.

Also known as: density formula · specific gravity calculator · mass over volume calculator · will it float calculator

Why water is exactly 1

Water's density of 1 g/cm³ is not a coincidence — the gram was originally defined as the mass of one cubic centimetre of water at its densest point.

The definition has since moved to more reproducible standards, so the equality is now approximate rather than exact, but it remains accurate to within a fraction of a percent and is the reason specific gravity works as a concept at all.

Floating

Anything less dense than the fluid floats. Oak at about 700 kg/m³ floats in fresh water; steel at 7,850 does not.

Seawater is denser at roughly 1,025 kg/m³, which is why a few things float at sea that sink in a lake, and why swimmers find salt water easier.

A steel ship floats because the relevant density is the whole hull including the air inside it, not the density of the steel. Average density is what matters, which is also why a submarine can change whether it floats by flooding or emptying its tanks.

Where to go next

The Density question rarely arrives on its own. These are the ones that usually come with it:

Pressure Calculator — From a force on an area, or from a depth of fluid.
Force Calculator — F = ma, in newtons, kilograms-force and pounds-force.
Speed Distance Time Calculator — Any one of the three from the other two, in four units.
Acceleration Calculator — Acceleration in m/s² and in g, which is the legible one.

Sources

Frequently asked questions

How do I calculate density?

Divide mass by volume. 1,000 kg in one cubic metre is 1,000 kg/m³, which is the density of water.

What is specific gravity?

Density relative to water. It is numerically identical to density in g/cm³, and anything under 1 floats.

Why does 1 g/cm³ equal 1,000 kg/m³?

Because a cubic metre holds a million cubic centimetres and a kilogram is a thousand grams. The factors cancel to exactly 1,000.

Will my material float?

If its density is below 1,000 kg/m³, in fresh water. Oak at about 700 floats; steel at 7,850 does not. Seawater is denser at roughly 1,025, so a few things float in it that sink in fresh.

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The one-line version

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