Density, mass and volume calculator
Pick what you want to find, enter the other two quantities in any common unit, and get the result in clear units with a note on whether it would float in water.
How this calculator works
Density tells you how much matter is packed into a given space. Lead and polystyrene can have exactly the same volume and wildly different masses, and density is the number that captures that difference. The calculator converts everything to kilograms and cubic metres first, does the sum, then shows the answer back in friendlier units.
It also compares the result with fresh water at 1000 kg/m³. Anything with a lower density floats and anything higher sinks, which is why a steel ship floats: its overall shape encloses so much air that the average density drops below water.
The formula behind it
- density = mass ÷ volume
- mass = density × volume
- volume = mass ÷ density
1 g/cm³ = 1000 kg/m³, and 1 mL = 1 cm³.
A worked example
A metal block has mass 540 g and volume 200 cm³. Density = 540 ÷ 200 = 2.7 g/cm³, which is 2700 kg/m³. That matches aluminium, and as it is denser than water it sinks.
Questions people ask
Why is 1 g/cm³ the same as 1000 kg/m³?
A cubic metre holds a million cubic centimetres and a thousand grams make a kilogram, so you multiply by 1,000,000 ÷ 1000 = 1000.
What is the density of water?
About 1 g/cm³ or 1000 kg/m³ for fresh water at around 4 degrees Celsius. Seawater is slightly higher, near 1025 kg/m³.
Why do hollow objects confuse density questions?
The formula gives the average density of the whole object, including any empty space. A hollow steel ball can float even though solid steel sinks.
Is density the same as weight?
No. Weight is a force and depends on gravity. Density is a property of the material and stays the same on the Moon.