Density Calculator
Calculate the density of any substance by entering its mass and volume. Used in chemistry, physics, and engineering to identify materials or check concentration of solutions.
About this calculator
Density is a physical property that describes how much mass is packed into a given volume. The formula is: density (ρ) = mass / volume. The standard SI unit is kg/m³, though g/mL is common in chemistry and is numerically equal to g/cm³. Density is intrinsic, meaning it does not change with sample size — a small piece of gold has the same density as a large one. It is widely used to identify unknown substances by comparing calculated density to known reference values. In fluid dynamics, density differences drive buoyancy and mixing behavior. Temperature and pressure affect density, especially in gases, so conditions should be noted when comparing values.
How to use
Imagine you have a liquid sample with a mass of 250 g and a volume of 200 mL. Apply the formula: density = mass / volume = 250 / 200 = 1.25 g/mL. This density is close to that of a sugar solution or certain acids. Enter 250 in the 'Mass' field and 200 in the 'Volume' field, and the calculator returns 1.25 g/mL instantly. You can then compare this value to reference tables to help identify the substance.
Frequently asked questions
How do I find the density of an irregularly shaped object?
For irregularly shaped solids, you can measure volume using the water displacement method: submerge the object in a graduated cylinder and record how much the water level rises. That rise in volume equals the object's volume. Then weigh the object on a scale to get its mass. Divide mass by displaced volume to find density. This technique is the same one Archimedes famously used and works for any solid that does not dissolve in water.
What is the density of water and why does it matter as a reference?
Pure water has a density of approximately 1.00 g/mL (or 1000 kg/m³) at 4°C, which is its maximum density. This value is used as a universal reference in science and engineering. Substances with a density greater than 1 g/mL will sink in water, while those less than 1 g/mL will float — a principle fundamental to buoyancy calculations. Water's density also defines specific gravity, which is the ratio of a substance's density to that of water.
Why does density change with temperature?
As temperature increases, most substances expand — their volume grows while mass stays the same, so density decreases. This is why hot air rises and why ice floats on liquid water (water is unusual in that it expands upon freezing). In gases, density changes are especially pronounced because gas molecules are far apart and highly responsive to temperature changes, as described by the ideal gas law. Accurate density measurements in science and industry always specify the temperature at which the measurement was taken.