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Free density calculator

Solve the density triangle instantly — enter any two of density, mass, or volume and get the third, with a 12-material reference table and SI and US units.

On this page10 sections

InputsLive

Mass (m)

Volume (V)

m³

Density (ρ)

kg/m³

Enter any two values; the third is calculated.

Result

Density

1,000 kg/m³

ρ = 1,000 kg/m³ | m = 1,000 kg | V = 1 m³

Mass (kg)1,000

Volume (m³)1

Density (kg/m³)1,000

Water reference1,000 kg/m³

Formula: ρ = m / V. Enter any two values and leave the third blank to solve for it. Density varies with temperature and pressure; values assume standard conditions.

Results are estimates. Consult a professional.

How it's calculated

How the density calculator works

Density measures how much mass is packed into a given volume — a lead fishing weight and a cork float can be the same size, but one sinks and one floats because their densities differ by a factor of roughly forty. This calculator solves the density triangle in all three directions: give it any two of density, mass, and volume and it returns the third. Enter in any unit; the calculator converts and reports in both SI (kg/m³, kg, m³) and common US units (lb/ft³, lb, ft³).

density (ρ) = mass (m) ÷ volume (V)

mass (m) = density (ρ) × volume (V)

volume (V) = mass (m) ÷ density (ρ)

Density definition and SI unit (kg/m³) from NIST SP 330 "The International System of Units (SI)." Reference densities verified against NIST Standard Reference Data and The Engineering ToolBox.

Example

Worked example: a block of steel

Example: find the mass of a steel block 0.5 m × 0.4 m × 0.2 m

An engineer needs the mass of a carbon-steel plate to check if a shelf can bear it. The plate dimensions are 0.5 m × 0.4 m × 0.2 m and steel's nominal density is 7,850 kg/m³. She knows density and volume — the calculator finds mass.

Step 1 — Calculate the volume

Volume = 0.5 × 0.4 × 0.2 = 0.04 m³.

Step 2 — Apply the mass formula

m = ρ × V = 7,850 × 0.04 = 314 kg.

314 kg (693 lb)

A steel plate that looks modest in size still weighs more than 300 kg. Swap the metal to aluminum (2,700 kg/m³) and the same block drops to 108 kg — less than a third of the weight.

Quick reference

Density of common materials

These are the nominal densities used in engineering and science references. Use them as starting points; actual density varies with temperature, alloy, and purity.

Material	Density (kg/m³)	Density (lb/ft³)	Relative to water
Air (sea level, 15 °C)	1.225	0.08	0.001
Fresh water (4 °C)	1,000	62.4	1.00
Seawater	1,025	64.0	1.03
Concrete	2,300	143.6	2.30
Aluminum	2,700	168.6	2.70
Steel (carbon)	7,850	489.8	7.85
Copper	8,960	559.4	8.96
Lead	11,340	708.0	11.34
Gold	19,320	1,206	19.32
Oak (dry)	720	44.9	0.72
Pine (dry)	530	33.1	0.53
Ethanol	789	49.3	0.79

Source: NIST Standard Reference Data and The Engineering ToolBox. Values at room temperature (~20 °C) unless noted. Densities vary with temperature and specific grade; confirm against a material data sheet for precision work.

When to use it

Practical uses for the density calculator

The density formula shows up whenever you need to reason about how heavy something will be, whether it will float, or how much space a given mass will fill. Common practical situations include estimating shipping weight from dimensions, checking whether a material will sink or float in a liquid, converting between volume and mass when buying materials in bulk, and identifying an unknown substance by measuring it against known density values.

Sink or float? — Any object denser than the liquid it is placed in will sink. An object less dense floats. Water is 1,000 kg/m³; anything below that floats, anything above sinks.
Shipping weight estimates — Know the volume from dimensions and the material? Multiply by density to get the mass before crating and quoting freight.
Bulk buying — Suppliers often sell liquids and aggregates by volume; the density tells you how many kilograms are in each litre or cubic foot.
Material identification — Measure a mystery metal's mass and volume, divide, and compare the result to the reference table to narrow down what it is.

Water = 1,000 kg/m³

Fresh water at 4 °C is the original density reference — it is exactly 1 g/cm³ by design. Keeping that anchor in mind makes every other density easy to put in perspective.

Accuracy

Accuracy and limitations

The arithmetic is exact given the inputs. The gap between a calculated result and a measured one almost always comes from the density value itself. Density changes with temperature (liquids and gases especially), varies between alloy grades, and differs between a porous sample and a solid one. Air at 0 °C is 1.293 kg/m³; at 30 °C it is 1.165 kg/m³ — an 10% difference from temperature alone.

For solids, use the nominal value from a material data sheet for planning; measure a calibrated sample if you need a precise result. For gases, density depends heavily on temperature and pressure — use the ideal gas law for accurate figures rather than a single tabulated value. For mixtures and composites, there is no single density; you would need to account for the volume fraction of each component.

Definitions

Density calculator definitions

Mass per unit of volume. SI unit is kg/m³. Also expressed as g/cm³ (numerically equal to g/mL) and lb/ft³. The Greek letter ρ (rho) is the conventional symbol.

The quantity of matter in an object, independent of gravity. SI unit is the kilogram (kg). Different from weight, which is the gravitational force acting on a mass (measured in newtons or pounds-force).

The three-dimensional space occupied by an object. SI unit is the cubic metre (m³). Commonly expressed as litres (L), millilitres (mL), cubic centimetres (cm³), or cubic feet (ft³).

The ratio of a material's density to the density of fresh water at 4 °C (1,000 kg/m³). Dimensionless. Steel at 7,850 kg/m³ has a specific gravity of 7.85. Values above 1 sink in water; below 1 float.

The density of a granular or powdered material including the air spaces between particles. Bulk density is always lower than the true (particle) density of the material. Used for aggregates, soil, and grain.

A memory aid showing the three forms of the formula in a triangle: cover the quantity you want to find and the remaining two show whether to multiply or divide. Density = mass ÷ volume; cover ρ and the triangle shows m over V.

About

About this density calculator

This calculator runs entirely in your browser. No numbers are sent to any server, and no account is needed. Results are shown immediately as you type, with both SI and US customary units.

Browse more science and measurement tools in our home & garden calculators collection, or explore the full library of free calculators.

Questions

Frequently asked questions about the free density calculator

A density calculator is a free online tool that helps you solve ρ = m/V — calculate density, mass, or volume given any two. Density is mass per unit volume. Same calculation works in any consistent units; SI is kg/m³. It runs entirely in your browser with instant results and no sign-up.

Specific gravity is density relative to water (so SG of water = 1). Multiply SG by 1000 kg/m³ to get density.

Buoyancy, structural load, shipping cost, material identification. A 1 m³ block of steel weighs 7.85× more than the same block of water.

Yes. Most materials expand when heated, reducing density. Water has an unusual maximum density at ~4 °C — it expands when freezing AND when heated above 4 °C.