Density is one of the key properties of materials – it determines whether an object sinks or floats in water, whether a piece of alloy is genuine or counterfeit, and how heavy a component made from a given material will be. The density calculator solves all three variants of the basic formula ρ = m/V, helping you identify unknown materials as well as calculate weights and volumes.
Step by Step: How to Use the Density Calculator
- Choose what to calculate: Do you want to find density (ρ), mass (m), or volume (V)?
- Set the units: Choose g/cm³ for solid objects or kg/m³ for building materials and gases. The calculator converts units automatically.
- Enter the known values: Fill in the two known quantities – for example mass 270 g and volume 100 cm³.
- Interpret the result: Densities below 1 g/cm³ float in water; densities above 1 g/cm³ sink. The calculator shows you this indication directly.
- Compare with materials: Use the built-in reference table to match the calculated result to a known material.
Practical Examples
Example 1 – Gold testing: An alleged gold bar weighs 193.1 g and has a measured volume of 12 cm³ (by water displacement). Calculated density: 193.1 / 12 = 16.09 g/cm³. Pure gold has a density of 19.32 g/cm³ – this piece is not solid gold, and is likely tungsten-plated (tungsten: 19.3 g/cm³).
Example 2 – Buoyancy in a swimming pool: A block of spruce wood weighs 940 g and measures 20 × 10 × 10 cm = 2,000 cm³. Density: 940 / 2,000 = 0.47 g/cm³. Since 0.47 < 1.0 (water), the block floats – and submerges to 47% of its volume.
Example 3 – Volume of an irregular object: A meteorite weighs 850 g; its density is assumed to be 7.8 g/cm³ (iron meteorite). Volume: V = 850 / 7.8 = 109 cm³. Submerge it in water and it displaces 109 ml – which lets you verify the assumption.
Density Formula: ρ = m / V
Formulas: ρ = m/V; m = ρ × V; V = m/ρ. Example: 1 L of water = 1 kg, ρ = 1 kg/L = 1 g/cm³. Aluminium: 2.7 g/cm³. Floating rule: ρ < 1 g/cm³ means the object floats in water.
Frequently Asked Questions (FAQ)
How do I measure the volume of an irregularly shaped object?
Use the water displacement method (Archimedes' principle): fill a measuring cylinder with a known amount of water, fully submerge the object and read the difference. 500 ml → 612 ml: volume = 112 ml = 112 cm³.
Why does the density of wood vary so much between species?
Wood is a porous natural material with very different cellular structures. Balsa (0.12 g/cm³) is extremely light due to large air cells; lignum vitae (1.4 g/cm³) actually sinks in water. On top of that, density can vary by up to 30% depending on moisture content.
Does the floating rule ρ < 1 g/cm³ always apply?
The rule applies to water with a density of exactly 1.0 g/cm³ (at 4 °C, pure water). In saltwater (ρ ≈ 1.025 g/cm³), objects float a little more easily; in other liquids, different thresholds apply. An object floats whenever its density is lower than that of the surrounding liquid.
