Gallons, liters, fluid ounces and cups
The US gallon is defined as 231 cubic inches, which makes it exactly 3.785411784 L. Every smaller US unit is a fraction of it: 1 gal = 4 quarts = 8 pints = 16 cups = 128 fl oz.
- US gallon: gasoline, milk, paint, water heaters.
- UK (imperial) gallon: 4.54609 L, about 20% larger; still used for fuel economy (mpg) in the UK.
- US fl oz: 29.57353 mL; drinks and cosmetics. A UK fl oz is slightly smaller (28.41 mL).
- US cup: 8 fl oz = 236.588 mL in recipes; US nutrition labels round it to 240 mL.
- Cubic feet: fridge and freezer capacity (1 ft³ = 28.3168 L = 7.48052 gal). Barrel: 42 gal = 158.987 L of crude oil.
1 US gal = 3.785411784 L (exact) 1 L = 0.264172 US gal
1 UK gal = 4.54609 L (exact) 1 US fl oz = 29.57353 mL
1 cup = 8 fl oz = 236.5882 mL 1 ft³ = 28.316846592 L
US gallons to liters table
| gal | L | UK gal |
|---|---|---|
| 1 gal | 3.7854 | 0.83267 |
| 2 gal | 7.5708 | 1.6653 |
| 3 gal | 11.356 | 2.498 |
| 5 gal | 18.927 | 4.1634 |
| 10 gal | 37.854 | 8.3267 |
| 12 gal | 45.425 | 9.9921 |
| 15 gal | 56.781 | 12.49 |
| 20 gal | 75.708 | 16.653 |
| 30 gal | 113.56 | 24.98 |
| 50 gal | 189.27 | 41.634 |
| 55 gal | 208.2 | 45.797 |
| 100 gal | 378.54 | 83.267 |
Worked example
A 12 fl oz soda can: 12 × 29.5735 = 354.88 mL, sold as 355 mL abroad. A 55-gallon drum holds 208.2 L.
Frequently asked questions
How many liters are in a gallon?
1 US gallon = 3.78541 L. A UK (imperial) gallon is 4.54609 L.
How many mL is 1 fl oz?
1 US fl oz = 29.5735 mL; 8 fl oz = 1 cup = 236.6 mL.
How many gallons is a cubic foot?
1 ft³ = 7.48052 US gallons = 28.3168 L.