Gallons to Cups Converter
Convert US gallons to US cups — sixteen cups to the gallon. Results update as you type; exact factors shown.
One US gallon is 16 US cups — see the exact factor, not a rounded rule of thumb.
How the gallons to cups converter works
Volumes convert through the litre (exactly 1 dm³). The US gallon is exactly 3.785411784 L (231 cubic inches); the imperial gallon is exactly 4.54609 L. A US fluid ounce is 29.5735 mL, an imperial fluid ounce 28.4131 mL; a US pint is 16 US fl oz, an imperial pint 20 imperial fl oz.
The UK is metric for most trade and science but keeps miles, pints, stone and mpg (with the imperial gallon) in daily life.
Common volume conversions
| From | To | Units |
|---|---|---|
| 0.125 US gal | 2 US cup | US gallons to US cups |
| 0.25 US gal | 4 US cup | US gallons to US cups |
| 0.5 US gal | 8 US cup | US gallons to US cups |
| 0.75 US gal | 12 US cup | US gallons to US cups |
| 1 US gal | 16 US cup | US gallon to US cups |
| 1.5 US gal | 24 US cup | US gallons to US cups |
| 2 US gal | 32 US cup | US gallons to US cups |
| 3 US gal | 48 US cup | US gallons to US cups |
| 4 US gal | 64 US cup | US gallons to US cups |
| 5 US gal | 80 US cup | US gallons to US cups |
| 10 US gal | 160 US cup | US gallons to US cups |
| 20 US gal | 320 US cup | US gallons to US cups |
Units in this converter and their exact factors
| Unit | Symbol | One unit in litres |
|---|---|---|
| millilitre | mL | 0.001 litre |
| litre | L | 1 litre |
| cubic metre | m³ | 1,000 litre |
| teaspoon (metric) | tsp | 0.005 litre |
| tablespoon (metric) | tbsp | 0.015 litre |
| cup (metric) | cup | 0.25 litre |
| US fluid ounce | US fl oz | 0.0295735296 litre |
| US cup | US cup | 0.2365882365 litre |
| US pint | US pt | 0.473176473 litre |
| US gallon | US gal | 3.785411784 litre |
| imperial fluid ounce | imp fl oz | 0.0284130625 litre |
| imperial pint | imp pt | 0.56826125 litre |
| imperial gallon | imp gal | 4.54609 litre |
| cubic foot | ft³ | 28.316846592 litre |
FAQFrequently asked questions about volume conversion
How many cups in a gallon?
Exactly 16 US cups.
How many cups in a half gallon?
8.
Is a UK gallon the same?
No — the imperial gallon is 4.546 L against the US gallon's 3.785 L, about 20% larger.
How many cups of water a day is a gallon?
Sixteen cups, which is the origin of the "gallon a day" hydration claim.
How many quarts in a gallon?
Four, and each quart is four cups.
Where these figures come from
- BIPM — The International System of Units (SI Brochure, 9th edition) — definitions of the base and derived units.
- NIST Special Publication 811 — Guide for the Use of the International System of Units — the exact conversion factors used here.
- National Physical Laboratory (NPL) — United Kingdom's national measurement authority.
Last checked: September 2026. Conversion factors are fixed by definition and do not change with tax years or regulations.