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What does this calculator estimate?
A 200 kg object with 0.5 cubic meters of volume has a density of 400 kg/m^3, or 0.4 g/cm^3. Density = mass / volume; g/cm^3 = kg/m^3 / 1,000.
- Density (kg/m^3) = mass (kg) / volume (m^3).
- Water's density is about 1,000 kg/m^3 (1 g/cm^3) at 4 C.
- Objects denser than water sink; less dense objects float (NIST).
What density measures
Density is how much mass fits in a given volume — a material property that identifies substances and predicts whether they float or sink. It's also the bridge between volume and mass in engineering and chemistry.
Limitations to watch for
Density changes with temperature (materials expand) and pressure (gases compress). The tool assumes uniform density — porous or composite objects have bulk densities that differ from their materials. Volume measurement method matters.
How to use it in practice
Use density to convert between volume and mass (mass = density × volume) or to check whether something floats. Compare measured density to reference tables to identify materials. Account for temperature for precision work.
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What density measures
Density is mass per unit volume: a 200 g object in 50 mL has a density of 4 g/mL. It is a material property that identifies substances, predicts buoyancy, and converts between mass and volume.
The buoyancy test
Objects denser than water (1 g/mL) sink; less dense float. A 2.7 g/cm³ aluminum block sinks; a 0.9 g/cm³ ice cube floats. The calculator's comparison to water makes the prediction instant.
Unit conventions
Density appears as g/cm³, kg/m³, g/mL, and lb/ft³ depending on the field: water is 1 g/cm³ = 1,000 kg/m³ = 62.4 lb/ft³. The calculator converts between the common units so comparisons stay valid.
A worked example
A 500 cm³ block weighs 1,350 g: density = 2.7 g/cm³ — aluminum. The same volume at 7,800 g is steel (7.8 g/cm³). The calculator returns the density and the likely material class.
Temperature matters
Density changes with temperature: materials expand when heated, lowering density. Fuel density, metal density tables, and ocean water all vary with temperature — use the temperature-appropriate value for precise work.
How this calculator works
Formula
Density ρ = mass ÷ volume. SI units: kg/m³; the tool also reports g/cm³ (kg/m³ ÷ 1000). Common references: water ≈ 1,000 kg/m³ (1 g/cm³), air ≈ 1.225 kg/m³ at sea level.
Worked example
A 200 kg object with a volume of 0.25 m³ has density = 200 ÷ 0.25 = 800 kg/m³, or 0.80 g/cm³ — it floats in water.
Assumptions to verify
- Mass and volume are measured in consistent SI units.
- The object's density is uniform.
- Temperature and pressure effects are ignored.
Frequently asked questions
What is density?
Mass per unit volume — how tightly packed the matter in a substance is. Water is about 1,000 kg/m³ (1 g/cm³).
How do I calculate density?
Divide mass by volume: ρ = m ÷ V. 200 kg ÷ 0.25 m³ = 800 kg/m³.
What units are used?
SI: kg/m³. The tool also reports g/cm³, which equals kg/m³ ÷ 1000 — handy because water is exactly 1 g/cm³.
Why do things float?
Objects float when they're less dense than the fluid. Wood (~600–900 kg/m³) floats in water (1,000); steel (7,850) sinks.
Does temperature change density?
Yes — heating expands most materials, lowering density. That's why hot air rises and why density measurements need a temperature reference.
How do I measure the density of an irregular object?
Measure mass, then volume by water displacement (Archimedes' principle): the volume of water displaced equals the object's volume.
What is bulk density?
Mass ÷ bulk volume including pores and voids — lower than the material's true density for powders, soils, and porous rocks.
What is the density of water?
About 1 g/cm³ or 1,000 kg/m³ at room temperature.
Will it float or sink?
Compare the object's density to the liquid's — denser sinks, less dense floats.
Cite this tool
BoringToolsKit. “Density Calculator.” boringtoolskit.com/density-calculator/ (reviewed 2026-08-25). Free to reference in articles, syllabi, and answer posts with a link.
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