Density describes how much mass is packed into a given volume, and it's a key property in material science, engineering, and everyday tasks like figuring out whether an object will float. This calculator takes mass in kilograms and volume in liters and returns density in both kg/m³ and g/cm³.
The formula
For 5 kg of a substance occupying 2 liters: density = 5 ÷ 2 = 2.5 kg/L, which is the same as 2,500 kg/m³ or 2.5 g/cm³ (since 1 kg/L equals exactly 1 g/cm³).
Worked examples
| Mass | Volume | Density |
|---|---|---|
| 1 kg | 1 L | 1,000 kg/m³ (like water) |
| 2.7 kg | 1 L | 2,700 kg/m³ (like aluminum) |
| 0.92 kg | 1 L | 920 kg/m³ (like ice) |
Why density matters
- Buoyancy: an object with a lower density than the surrounding fluid will float; water's density (1,000 kg/m³) is the usual reference point.
- Material identification: density is often used as a quick, non-destructive way to help identify an unknown material.
- Shipping and logistics: density affects how goods are packed and priced for volumetric versus weight-based shipping.
Common mistakes
- Mixing unit systems. Make sure mass is in kilograms and volume in liters before calculating, or convert consistently afterward.
- Confusing density with specific gravity. Specific gravity is density relative to water's density and has no units, while density itself always carries units like kg/m³.
Frequently asked questions
How do I calculate density?
Divide mass by volume: density = mass ÷ volume. Using kilograms and liters gives density directly in kg/L, which equals g/cm³.
What's the difference between kg/m³ and g/cm³?
They represent the same physical density using different unit scales; the numeric value in g/cm³ is always 1,000 times smaller than the value in kg/m³.
Why does a substance float or sink based on density?
An object floats in a fluid when its density is lower than the fluid's density, and sinks when its density is higher — this is the basis of buoyancy.