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. Choose the units to convert from and to.
  2. Enter a value — the converted result updates instantly.
  3. Click Copy to copy the result to your clipboard.

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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