Free Volume Converter
Convert volume units instantly — liters, gallons, milliliters, fluid ounces, cups, pints, quarts. Type into any field and all update. Free, symmetrical.
Exact Conversion Formula & Multipliers
Volume hinges on one frequently misunderstood fact: the US gallon (3.785411784 liters, exact) and the UK imperial gallon (4.54609 liters, exact) are different sizes — a UK gallon is about 20% larger. From these, 1 US fluid ounce = 29.5735295625 mL while 1 UK fluid ounce = 28.4130625 mL. This converter tracks both gallon systems separately so recipe and fuel-economy figures don't silently mix the two.
Practical Real-World Scenarios
- Automotive: fuel tank capacities and fuel economy figures differ between US and UK sources because they're built on different gallon definitions, not just different units.
- Cooking and brewing: a US recipe's cup or gallon measurement will not match a UK or Australian recipe using the same word, tripping up home bakers following international recipes.
- Shipping and industry: bulk liquids like fuel and chemicals are traded in liters internationally but often quoted in gallons in US contracts, requiring careful conversion in invoices.
Historical & Technical Background
The gallon has a genuinely tangled history: medieval England had separate gallons for wine, ale, and grain before the 1824 Imperial system standardized a single UK gallon, while the US retained the older wine gallon of 231 cubic inches as its standard. The liter, part of the metric system since 1795, was defined as the volume of one kilogram of water, giving it a clean relationship to both volume and mass units that the historical gallon variants never had.
Precision & Accuracy Statement
Conversion factors use the exact defined values given in NIST Special Publication 811 and the BIPM SI Brochure wherever such a definition exists (for example 1 lb = 0.45359237 kg, 1 in = 2.54 cm, 1 US gal = 3.785411784 L, g₀ = 9.80665 m/s²); derived factors are computed from those definitions rather than copied as rounded figures. Results are calculated in double-precision floating point and shown to 10 significant digits, so the last digit can differ by one unit of rounding. The rounded figures in the text and tables above are for reading convenience.
How This Converter Works
Volume is used in cooking, chemistry, fuel, and everyday liquids. The US and UK use different gallon sizes, and cooking uses cups and spoons. Our converter handles 13 volume units simultaneously.
Common Conversions
| Liters (L) | US Gallons | US Fluid Oz | Context |
|---|---|---|---|
| 0.237 L | 0.0625 gal | 8 fl oz | One US cup |
| 0.473 L | 0.125 gal | 16 fl oz | One US pint |
| 0.946 L | 0.25 gal | 32 fl oz | One US quart |
| 1.0 L | 0.264 gal | 33.81 fl oz | One liter |
| 3.785 L | 1.0 gal | 128 fl oz | One US gallon |
| 4.546 L | 1.201 gal | 153.7 fl oz | One UK gallon (= 160 UK fl oz) |