What is the density formula?

Density is defined as mass divided by volume — ρ = m ÷ V. Rearranged, mass = ρ × V and volume = m ÷ ρ. In SI units density is measured in kg/m³, but g/cm³ is equally common for solids and liquids because pure water equals exactly 1 g/cm³.

How do I convert g/cm³ to kg/m³?

Multiply by 1000. One gram per cubic centimetre is the same as one thousand kilograms per cubic metre. For example, steel at 7.85 g/cm³ equals 7850 kg/m³. The calculator handles this conversion automatically whichever unit pair you choose.

What is the density of water?

Pure (distilled) water reaches its maximum density of 1000 kg/m³ (exactly 1 g/cm³) at 3.98 °C. At 20 °C it is about 998 kg/m³, and seawater averages around 1025 kg/m³ due to dissolved salts. The floatation check in this calculator uses 1000 kg/m³ as the reference.

How does the floatation (buoyancy) check work?

An object floats when its average density is less than the density of the surrounding fluid. This calculator compares the computed density against 1000 kg/m³ (fresh water) and reports whether the object would float or sink. For seawater (1025 kg/m³) adjust your comparison manually — objects that barely sink in fresh water can float in the sea.

Why does the calculator convert everything to SI first?

Working in SI base units (kg for mass, m³ for volume, kg/m³ for density) prevents unit-mismatch errors. Once all values share a common system the formula ρ = m ÷ V is applied once, and then the result is converted back into whichever display unit you selected. Doing the conversion at the start and the display at the end is the standard engineering approach.

Which unit systems are supported?

Density — kg/m³, g/cm³, g/mL, kg/L, lb/ft³, lb/in³. Mass — kg, g, mg, metric tonne (t), pound (lb), ounce (oz). Volume — m³, cm³, mL, litre (L), ft³, in³, US gallon. Mix units freely; the calculator converts each input independently.

Density Calculator — Gera Tools

Density is one of the most fundamental physical quantities — the mass packed into each unit of volume. Whether you need to identify a mystery material, check whether an object will float, plan a shipping weight, or work through a chemistry problem, the three-way formula ρ = m ÷ V (or its rearrangements m = ρ × V and V = m ÷ ρ) is your starting point.

This tool solves for whichever variable you choose, shows every conversion and arithmetic step, and places your result in context against a library of common materials — all running entirely in your browser with nothing uploaded.

How it works

The relationship between density (ρ), mass (m), and volume (V) is:

ρ = m ÷ V

Rearranged for the other two unknowns:

Solve for	Formula	SI unit
Density (ρ)	ρ = m ÷ V	kg/m³
Mass (m)	m = ρ × V	kg
Volume (V)	V = m ÷ ρ	m³

The calculator converts every input to SI base units first (kilograms and cubic metres), applies the formula, then converts the result into your chosen output unit. The “Working” panel below the result shows each conversion step explicitly so you can verify the arithmetic yourself or copy it into a lab report.

Supported unit coverage is intentionally wide: density in kg/m³, g/cm³, g/mL, kg/L, lb/ft³ and lb/in³; mass in kg, g, mg, metric tonnes, pounds and ounces; volume in m³, cm³, mL, litres, ft³, in³ and US gallons. You can freely mix unit families — for example, supply a mass in pounds and a volume in litres and the calculator handles the cross-conversion without any extra steps from you.

Worked example — finding the density of an iron rod

An iron rod has a mass of 7.85 kg and occupies a volume of 1000 cm³ (= 0.001 m³).

Step 1 — convert volume to SI:

1000 cm³ × 10⁻⁶ = 0.001 m³

Step 2 — apply the formula:

ρ = 7.85 kg ÷ 0.001 m³ = 7850 kg/m³

Step 3 — express in g/cm³ (divide by 1000):

7850 ÷ 1000 = 7.85 g/cm³

Comparing against the reference table, 7850 kg/m³ matches steel almost exactly. Iron and low-carbon steel share a density of roughly 7.85–7.87 g/cm³, confirming the result. Because this is much greater than water (1000 kg/m³), the rod sinks.

Reverse problem — finding the volume of a gold ingot

A standard London Good Delivery gold bar has a mass of 400 troy ounces (≈ 12.44 kg). Gold’s density is 19 300 kg/m³.

V = m ÷ ρ = 12.44 kg ÷ 19 300 kg/m³ ≈ 0.000 645 m³ ≈ 645 cm³

That is roughly the volume of a 500 mL water bottle — surprisingly compact for something weighing nearly 12.5 kg.

Key reference values

Material	Density (g/cm³)	Notes
Hydrogen gas	0.000 09	Lightest element at STP
Air (20 °C)	0.001 2	Reference for aerostatics
Balsa wood	0.12	Lightest common structural wood
Ethanol	0.789	Common solvent
Fresh water	1.000	Reference density at 4 °C
Seawater	1.025	Average ocean surface
Concrete	2.3	Typical structural mix
Aluminium	2.7	Lightest common structural metal
Steel	7.85	Low-carbon grade
Lead	11.34	Dense shielding material
Mercury	13.53	Densest common liquid
Gold	19.3	Dense; difficult to counterfeit
Osmium	22.59	Densest naturally occurring element

The interactive chart in the calculator overlays your computed density on a bar chart of six representative reference materials, giving an immediate visual sense of where your substance sits on the density scale.