Density Calculator
Density calculator (ρ = m/V): solve for density, mass or volume in SI units, with a g/cm³ and US/imperial readout. Curriculum-aligned.
Density Calculator
Enter any two values and leave the third blank — the calculator solves for it. Results are in SI units, with a g/cm³ and US/imperial readout below.
- Curriculum
- English (global) — Cambridge International + IB
- Built against
- Cambridge IGCSE Physics 0625 + IB MYP (2023–2025) — Density
- Unit system
- SI primary; US/imperial readout below
- First published
- 1 Jun 2026
- Last updated
- 1 Jun 2026
View authoritative scientific sources
- NIST SP 811 (2008), §3 — units & conversions
- BIPM SI Brochure, 9th edition (2019)
- CRC Handbook of Chemistry and Physics — densities of materials
- Density — Encyclopædia Britannica
⚠️ Educational use only — see full disclaimer
EDUCATIONAL USE DISCLAIMER
This calculator is provided for educational and reference purposes only. It is not a substitute for instruction from a qualified teacher, your prescribed textbook, or your school's official curriculum materials.
When preparing for examinations, always cross-check our calculations and notation against your current syllabus and your teacher's guidance. Syllabus conventions and accepted notation vary between curricula and may change between examination years.
If you believe any calculation, notation, or curriculum reference in this tool is inaccurate, please let us know via the feedback button. We review feedback promptly and update tools when verified corrections are needed.
RECATOOLS accepts no liability for academic, examination, professional, or research outcomes arising from use of this tool.
How to Use the Density Calculator
Pick your curriculum
Use the curriculum pills above to match your syllabus (Cambridge, SEAB, SPM, SBMPTN, 高考, 學測 or HKDSE). Terminology, the worked example and the whole page follow your selection.
Enter any two values
Type two of density, mass and volume — leave the one you want to find blank. Each field has a unit selector (kg/m³ or g/cm³; kg, g, lb; m³, L, cm³).
Read the SI result
The answer is shown in SI units (kg/m³), with a dimmed g/cm³ and US/imperial readout below that you can hide.
Check against your syllabus
The Tool Information block shows exactly which syllabus this is built against. Spot something off? Use the feedback button — we review every report.
Density, in Your Curriculum's Words
Density (Density = Mass ÷ Volume)
Example: A block of aluminium has mass 270 g and volume 100 cm³.
Given: m = 270 g, V = 100 cm³. Using ρ = m / V:
ρ = 270 ÷ 100 = 2.70 g/cm³ = 2700 kg/m³
Density is the mass per unit volume of a material: ρ = m / V. The SI unit is the kilogram per cubic metre (kg/m³); chemists often use grams per cubic centimetre (g/cm³), where 1 g/cm³ = 1000 kg/m³. Rearranged, the same relation gives mass (m = ρV) or volume (V = m / ρ), which is why this tool solves for whichever value you leave blank.
An object less dense than a fluid floats in it — which is why ice floats on water. SI is always the primary result, with a dimmed g/cm³ and US/imperial readout for students whose textbooks use those units. All calculation happens in your browser — nothing is uploaded.
The reason an iron nail sinks but an iron ship floats is not the density of the metal, but the average density of the whole ship including the air inside it.
10 Facts About Density
Density ρ = m / V — mass per unit volume.
The SI unit is kg/m³; chemists use g/cm³ (1 g/cm³ = 1000 kg/m³).
Water is about 1000 kg/m³ (1.00 g/cm³) at 4 °C.
An object less dense than a fluid floats in it.
Density usually falls as temperature rises (matter expands).
Osmium and iridium are the densest elements (~22,600 kg/m³).
Air is about 1.2 kg/m³ at room temperature.
Relative density (specific gravity) compares to water — unitless.
Ice (~917 kg/m³) is less dense than water, so it floats.
This calculator runs in your browser — your working stays private.
Frequently Asked Questions
- ρ = m / V — density equals mass divided by volume. Rearranged, m = ρV and V = m / ρ. The calculator solves for whichever value you leave blank, and shows the answer in kg/m³ with a g/cm³ and imperial readout.
- The SI unit is the kilogram per cubic metre (kg/m³). You may enter g/cm³, lb/ft³ or lb/gal for density; kg, g or lb for mass; and m³, L or cm³ for volume. The tool converts everything to SI first, then shows the result in SI with a dimmed g/cm³ and US/imperial readout.
- Yes. Enter any two of density, mass and volume and leave the third blank — the calculator rearranges ρ = m / V and solves for the missing value.
- Density has units (kg/m³). Relative density, or specific gravity, is the ratio of a material's density to that of water, so it is unitless. A material with a relative density below 1 floats on water.
- The physics — ρ = m / V — is identical worldwide. What changes is the terminology. For example "density" is 密度 in Chinese, "ketumpatan" in Malay and "massa jenis" in Indonesian — but the calculated value is the same.
- The smaller of your inputs' significant figures, capped at five, switching to scientific notation for very large or very small numbers — standard exam practice.
- An object floats when its average density is less than the surrounding fluid, and sinks when it is greater. This is why a steel ship floats: the average density of the hollow hull, including the air inside, is less than water.
- The Tool Information block lists the exact syllabus for your selected curriculum (e.g. SEAB O-Level Physics 6091 or SPM Fizik 4531). It is a study aid, not a substitute for your official syllabus or teacher.
- Completely free, no account or usage limit. It runs entirely in your browser and collects no data.
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