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⚖️ Density Calculator

Calculate density (ρ = m / V) from mass and volume, or reverse-calculate mass or volume from a known density. Includes specific gravity.

Calculation Mode

Mass

Density

Volume

What is this tool?

Density is a fundamental intensive property of matter that expresses how much mass is packed into a given volume, defined by the ratio ρ = m / V, where ρ (the Greek letter rho) is density, m is mass and V is volume. The SI unit of density is kilograms per cubic metre (kg/m³), but in laboratory and everyday contexts grams per cubic centimetre (g/cm³) is more common; the two are related by 1 g/cm³ = 1000 kg/m³. Because density is intensive, it does not depend on the amount of material — a drop of mercury and a swimming pool of mercury have the same density even though their masses and volumes differ enormously. Density determines whether an object floats or sinks: a substance less dense than water (ρ < 1.0 g/cm³) will float, while a denser substance sinks, which is why cork (0.24 g/cm³) bobs on the surface and a steel nail (7.87 g/cm³) drops to the bottom. Temperature and pressure both affect density because most materials expand when heated and contract when cooled, so precise density values always quote the measurement temperature. This density calculator implements the core relationship in all three directions — calculate density from mass and volume, calculate mass from density and volume, or calculate volume from mass and density — and also reports specific gravity, the dimensionless ratio of a material's density to the density of water at 4 °C (≈ 1.0 g/cm³). Specific gravity is widely used in brewing, gemology and medicine because it can be measured with a hydrometer without knowing the absolute density of water. For related calculations you may find our molarity calculator useful when converting between mass and molar concentration, or the pH calculator for acid-base work. The molecular weight calculator pairs well when you need the molar mass of a compound, and physics-oriented users can explore the acceleration calculator and force calculator for mechanics problems involving dense objects.

How it works

The calculator has three modes selectable from a drop-down menu. In **Calculate Density** mode you enter the mass and the volume and the tool returns ρ = m / V together with the specific gravity SG = ρ / 1.0. In **Calculate Mass** mode you enter the density and the volume and the tool returns m = ρ × V. In **Calculate Volume** mode you enter the mass and the density and the tool returns V = m / ρ. Unit selectors let you mix and match mass units (g, kg) and volume units (mL, cm³, m³, L), and the calculator converts everything internally before applying the formula. The reference table below lists densities for five common materials at room temperature (20 °C, 1 atm): | Material | Density (g/cm³) | Density (kg/m³) | Notes | |---|---|---|---| | Water (4 °C) | 1.000 | 1000 | Reference for specific gravity | | Gold | 19.32 | 19,320 | Among the densest metals | | Iron | 7.87 | 7870 | Structural steel is similar | | Aluminium | 2.70 | 2700 | Lightweight structural metal | | Air (20 °C) | 0.001225 | 1.225 | Gases are ~1000× less dense than liquids | For example, a 500 g block of aluminium occupies V = m / ρ = 500 / 2.70 ≈ 185.2 cm³, and a 100 cm³ sample of gold has a mass of m = ρ × V = 19.32 × 100 = 1932 g.

How to use

Select the mode — calculate density, mass, or volume.
Enter the known values (mass + volume, density + volume, or mass + density).
Choose the appropriate units for mass (g or kg) and volume (mL, cm³, m³, or L).
Review your inputs — temperature-sensitive measurements should note the reference temperature.
Click Calculate to see the result and specific gravity (in density mode).

Frequently Asked Questions

What is the difference between density and specific gravity?

Density is an absolute quantity with units of mass per volume (e.g. g/cm³ or kg/m³). Specific gravity is a dimensionless ratio of a material''s density to the density of water at 4 °C (≈ 1.0 g/cm³). Because specific gravity is a ratio, it has the same numeric value regardless of whether you use g/cm³ or kg/m³, making it convenient for cross-unit comparisons.

Why does the density of water change with temperature?

Water molecules pack slightly differently at different temperatures. Water reaches its maximum density of about 0.99997 g/cm³ at 4 °C and expands both when cooled below 4 °C (toward freezing) and when heated. This unusual behaviour is why ice floats on liquid water and why lakes freeze from the top down, insulating aquatic life below.

How do I find the density of an irregularly shaped object?

Use the water-displacement method: partially fill a graduated cylinder with water, record the level, submerge the object and record the new level. The difference in levels is the object''s volume. Divide the object''s dry mass by that volume to obtain density. For objects lighter than water, use a sinker to push them under or switch to a pycnometer.

What does a negative specific gravity mean?

Specific gravity cannot be negative for ordinary matter. If you obtain a negative value, a sign error was made in entering mass or volume, or a negative density was used. Re-check your inputs — mass, volume and density are always positive for real materials.

Why are gases so much less dense than solids and liquids?

In a gas the molecules are separated by large average distances (roughly 10 times their own diameter), so most of the volume is empty space. In solids and liquids the molecules are essentially in contact. Compressing a gas reduces the empty space and raises the density proportionally, which is why gas density depends strongly on pressure as well as temperature.

Can I use this calculator for bulk density of powders?

Yes, but be aware that bulk density includes the air spaces between particles and is therefore lower than the true (skeletal) density of the solid material. A powder''s bulk density also depends on how tightly it is packed (tapped vs untapped), so always specify the measurement method when reporting bulk-density values.

Does this calculator work for mixtures and alloys?

Yes, as long as the total mass and total volume of the mixture are known. The result is the average (bulk) density of the mixture. For alloys and solutions the density is generally not a simple weighted average of the component densities because mixing can change the packing; measure the mixture's mass and volume directly for the most reliable result.

Disclaimer: This density calculator is provided for educational and general-information purposes. Engineering, medical or safety-critical decisions should rely on certified material data sheets and laboratory measurements, not on generic textbook density values.

Tips & Advice

Always quote the temperature alongside a density value because most materials expand when heated — the density of water changes from 0.99987 g/cm³ at 0 °C to 0.99821 g/cm³ at 20 °C, which is small but matters for precise hydrometer readings. When measuring the density of an irregular solid, the water-displacement method gives volume directly: record the water level in a graduated cylinder before and after submerging the object, and the difference is the object's volume. For porous or absorbent materials, coat them with a thin waterproof layer first or the displaced water will seep into pores and understate the volume. Specific gravity has no units, so it is convenient for comparing materials across different unit systems, but remember it is referenced to water at 4 °C — using a different reference temperature shifts the value slightly. For gas density, remember that pressure matters as much as temperature (ideal gas law: ρ = PM/RT), so a gas density quoted without a pressure is incomplete. If you are working with solutions and need molar concentration rather than mass concentration, switch to the molarity calculator after determining the density.

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