Core answer: 1 L = 1,000 mL = 1 dm³; 1 m³ = 1,000 L. US vs UK differ: 1 US gallon = 3.785 L, 1 UK (imperial) gallon = 4.546 L — 20% apart. Cooking: 1 US cup = 236.6 mL, 1 tbsp = 15 mL, 1 tsp = 5 mL. A standard 20-ft shipping container holds ~33 m³ ≈ 33,000 L.
The core tables
| Unit | Equals |
|---|---|
| 1 mL | 1 cm³ (cc) |
| 1 L | 1,000 mL = 1 dm³ |
| 1 m³ | 1,000 L = 1 tonne of water |
| Unit | Liters |
|---|---|
| 1 US cup | 0.2366 |
| 1 US pint | 0.473 |
| 1 US quart | 0.946 |
| 1 US gallon | 3.785 |
| 1 UK pint | 0.568 |
| 1 UK gallon | 4.546 |
| 1 oil barrel | 159 L (42 US gal) |
Worked examples
Example 1 — Water heater. An 80 L heater holds 80 kg of water (1 L water = 1 kg) — confirm the wall brackets are rated for it.
Example 2 — Aquarium. A 60 × 30 × 36 cm tank: 64.8 L nominal; with substrate and 90% fill, ~55 L actual — size the filter for ~55 L, and the stand for 60+ kg.
Example 3 — US recipe. "2 cups of flour" = 473 mL ≈ 250 g of flour (flour ≈ 0.53 g/mL — volume-to-weight needs density, see the cooking guide).
Example 4 — Rain on a roof. 10 mm of rain on a 100 m² roof: 100 × 0.01 = 1 m³ = 1,000 L of harvestable water per rainfall.
Example 5 — Moving. A 4.2 m box truck ≈ 16–18 m³ usable; a 3-bedroom home typically needs 25–35 m³ — plan two trips or a bigger truck.
Common mistakes and myths
- US vs UK gallons — a "5-gallon water jug" is 18.9 L (US), not 22.7 L (UK); always check the context country.
- Fluid ounces vs weight ounces — 1 fl oz = 29.6 mL (volume); 1 oz = 28.35 g (mass); they coincide only for water.
- "cc" confusion — 1 cc = 1 mL exactly (medicine, engines); a 2.0 L engine has 2,000 cc displacement.
- Liters of fridge ≠ usable shelf space — a 500 L fridge has maybe 60% usable volume after shelves and air gaps.
- Forgetting water's magic number — 1 L = 1 kg only for water (and milk, roughly); 1 L of oil ≈ 0.92 kg, 1 L of honey ≈ 1.4 kg.