What is the density of water?
1000 kg/m³ (or 1 g/cm³) at 4°C. This is the standard reference for relative density (specific gravity).
Density Calculator
ρ = m/V
Calculate density from mass and volume. ρ = m/V — mass per unit volume.
Calculate
Enter values above to calculate
How it calculates
1
ρ = m / V
2
m in kg, V in m³
3
Result in kg/m³
Formula
ρ = m/V
Variable Table
| Symbol | Quantity | SI Unit |
|---|---|---|
| ρ | Density | kg/m³ |
| m | Mass | kg |
| V | Volume | m³ |
How to Use This Calculator
This density calculator is built for quick physics checks and worked-problem review. Enter values in the units shown beside each input, then compare the result with the formula and variable table before using it in a longer solution. The calculator does the arithmetic, but the physics still depends on choosing a model that matches the situation.
Start by identifying the system, the known quantities, and the quantity you want to find. If a value is given in a non-SI unit, convert it before substitution. A correct numerical answer with mixed units can still be physically wrong, especially when squared units, inverse seconds, charges, temperatures, or distances are involved.
Assumptions and Limits
The formula ρ = m/V is a model, not a universal description of every possible case. It assumes the quantities in the variable table are the relevant quantities for the problem and that hidden effects are either negligible or already included in the inputs. If friction, drag, relativistic speeds, changing fields, non-constant temperature, or geometry-specific effects matter, check whether a more complete model is needed.
Use the result as a magnitude and units check. Ask whether the answer has the right sign, whether it grows or shrinks when an input changes, and whether the limiting cases make sense. Setting an input to zero, doubling a quantity, or using a very large value is often enough to catch a formula choice or unit mistake before it reaches a final answer.
Worked Example
2 kg of a substance occupies 0.001 m³ (1 litre). Find density.
Step 1: ρ = m / V
Step 2: ρ = 2 / 0.001
Answer: ρ = 2000 kg/m³ (twice the density of water)
Common Mistakes
- Water has ρ = 1000 kg/m³ = 1 g/cm³ — a useful benchmark
- 1 litre = 0.001 m³; 1 g/cm³ = 1000 kg/m³
- Objects with ρ less than the fluid float; denser objects sink
Related
Frequently Asked Questions
Why do some objects float?
An object floats if its average density is less than the fluid's. This follows from Archimedes' principle.