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Density Calculator

Solves ρ = m / V for whichever of density, mass or volume is omitted, and reports density in kg/m³ and g/cm³, volume in litres and cm³, and the specific gravity relative to water.

When to use

You know two of mass, volume and density of an object or substance and need the third, e.g. the mass of a steel block, the volume of a litre of oil, or whether an object floats.

Do not use when: The substance is a gas whose density depends strongly on pressure and temperature (use ideal-gas-law), or you need the volume of a shape first (use sphere, cylinder or rectangular-prism).

Formula

density_kg_m3 = mass_kg / volume_m3; mass_kg = density_kg_m3 × volume_m3; volume_m3 = mass_kg / density_kg_m3; density_g_cm3 = density_kg_m3 / 1000; specific_gravity = density_kg_m3 / 1000

Inputs

Parameter	Type	Unit	Required	Description
`mass_kg`	number	kg	no	Mass in kilograms (1 g = 0.001 kg). Omit to solve for it. Range: ≥ 0
`volume_m3`	number	m³	no	Volume in cubic metres (1 L = 0.001 m³, 1 cm³ = 1e-6 m³). Omit to solve for it. Range: > 0
`density_kg_m3`	number	kg/m³	no	Density in kg/m³ (1 g/cm³ = 1000 kg/m³; water ≈ 1000, steel ≈ 7850, aluminium ≈ 2700). Omit to solve for it. Range: > 0

Outputs

Output	Type	Unit	Description
`solved_for`	string		Which quantity was computed: density_kg_m3, mass_kg or volume_m3.
`density_kg_m3`	number	kg/m³	ρ = m / V.
`density_g_cm3`	number	g/cm³	Density in grams per cubic centimetre (= kg/L).
`mass_kg`	number	kg	Mass in kilograms.
`mass_g`	number	g	Mass in grams.
`volume_m3`	number	m³	Volume in cubic metres.
`volume_l`	number	L	Volume in litres.
`volume_cm3`	number	cm³	Volume in cubic centimetres.
`specific_gravity`	number		Density relative to water at 1000 kg/m³; below 1 the object floats in water.
`floats_in_water`	boolean		True when the density is below 1000 kg/m³.

Example

2 kg in 2.5 L: {"mass_kg":2,"volume_m3":0.0025} → {"solved_for":"density_kg_m3","density_kg_m3":800,"density_g_cm3":0.8,"volume_l":2.5,"specific_gravity":0.8,"floats_in_water":true}

1 L of steel (7850 kg/m³): {"density_kg_m3":7850,"volume_m3":0.001} → {"solved_for":"mass_kg","mass_kg":7.85,"mass_g":7850,"floats_in_water":false}

GET https://tttkmbb.com/api/v1/calculate/density-mass-volume?mass_kg=2&volume_m3=0.0025

Machine access

API: GET https://tttkmbb.com/api/v1/calculate/density-mass-volume (query parameters) or POST with a JSON body {"inputs": {...}}
Schema: https://tttkmbb.com/api/v1/calculators/density-mass-volume · Markdown: https://tttkmbb.com/physics/density-mass-volume.md · JSON definition: https://tttkmbb.com/physics/density-mass-volume.json
MCP: server https://tttkmbb.com/mcp, tool run_calculator with calculator_id="density-mass-volume"
OpenAPI operationId: solve_density
Freshness: static. Authentication: none. Rate limit: fair use (see rate limits).

Sources

Wikipedia – Density (reference)
NIST Special Publication 811 – Guide for the Use of the SI, Appendix B (conversion factors) (standard)

FAQ

How do I enter volume in litres or cm³?

Convert to m³ first: litres ÷ 1000, cm³ ÷ 1,000,000. The outputs report the volume in L and cm³ as well.

Is specific gravity the same as density in g/cm³?

Numerically almost: specific gravity is density divided by that of water (about 1000 kg/m³ at 4 °C), so it is dimensionless while g/cm³ has units.

Related calculators

Pressure Calculator — Force and pressure exerted by a mass.
Sphere Calculator — Volume of a sphere for the density formula.
Cylinder Calculator — Volume of a cylinder for the density formula.