The formula
L = m³ × 1,000
Where the factor comes from — each unit by its definition, then its size in SI:
1 m³ is the SI unit of volume.1 L = m³ / 1000 = 0.001 m³
Dividing the two SI sizes gives the factor: 1,000, exact — every step above is a definition, not a measurement. The reverse factor is 0.001.
The cubic metre is the SI unit of volume; the litre is exactly one thousandth of it. The US and UK gallons are different sizes, which is why a fuel-economy figure in mpg depends on which country printed it.
Worked examples
- A soft-drink bottle: 0.002 m³ = 2 L — 0.002 × 1,000 = 2
- A paint bucket (5 US gal): 0.0189271 m³ = 18.9271 L — 0.0189271 × 1,000 = 18.9271
- A water tank: 1 m³ = 1,000 L — 1 × 1,000 = 1,000
- A drinks can (330 mL): 0.00033 m³ = 0.33 L — 0.00033 × 1,000 = 0.33
Frequently asked questions
How many litres is 1 m³?
1 m³ = 1,000 L, exactly, from the unit definitions.
How do I convert litres back to cubic metres?
Divide by 1,000 — or multiply by 0.001: 1 L = 0.001 m³.