Volume Converter — Liters, Gallons, Cups & More

Convert between liters, US gallons, cups, fluid ounces, cubic meters, and more with exact NIST factors.

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How this conversion works. Every unit is converted through the liter using exact US-customary and SI factors from NIST Special Publication 811.

How to use

  1. Pick the unit you are converting from, such as Cubic meter (m³) or Liter (L).
  2. Type the value and every other unit updates as you type.
  3. Copy the figure you need, or use the swap button to reverse the direction, Cubic inch (in³) included.

Frequently asked questions

How do I convert us gallon to liter?

1 us gallon = 3.78541 liter. Choose "US gallon (gal)" as From and "Liter (L)" as To, type a value, and the result updates instantly.

Is a US gallon the same as a UK gallon?

No. A US gallon is exactly 3.785411784 L; an imperial (UK) gallon is exactly 4.54609 L — about 20% larger. This tool includes both.

How many milliliters are in a US cup?

A US customary cup is exactly 236.5882365 mL (1/16 of a gallon). US recipe "legal" cups are rounded to 240 mL on nutrition labels.

Is my data sent to a server?

No. Conversions run entirely in your browser using fixed factors — nothing is uploaded or logged.

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