Cups to Gallons
Convert cups (cup) to gallons (gal). Both measure capacity and volume, and the conversion comes up in cooking, chemistry, fuel work.
The Formula
``
gallons = cups × 0.0625
cups = gallons × 16
`
One cup is 0.0625 gallons, and one gallon is 16 cups.
Conversion Table
| Cups | Gallons |
|---|---|
| 1 cup | 0.0625 gal |
| 2 cup | 0.125 gal |
| 5 cup | 0.3125 gal |
| 10 cup | 0.625 gal |
| 25 cup | 1.5625 gal |
| 50 cup | 3.125 gal |
| 100 cup | 6.25 gal |
| 500 cup | 31.25 gal |
| 1,000 cup | 62.5 gal |
The Other Direction
| Gallons | Cups |
|---|---|
| 1 gal | 16 cup |
| 2 gal | 32 cup |
| 5 gal | 80 cup |
| 10 gal | 160 cup |
| 25 gal | 400 cup |
| 50 gal | 800 cup |
| 100 gal | 1,600 cup |
| 500 gal | 8,000 cup |
| 1,000 gal | 16,000 cup |
What Each Unit Is
Cups (cup) — the US customary cup: exactly 240 millilitres in nutrition labelling, 236.588 mL legally. An American cooking measure standardised by Fannie Farmer in the 1890s.
Gallons (gal) — the US liquid gallon: exactly 3.785411784 litres. The English wine gallon of 231 cubic inches, kept by the US after Britain moved on in 1824.
A Sense of Scale
A coffee mug holds about 1.5 cups- US recipes measure everything in cups
- A US milk jug is 1 gallon
- A car tank is 12–16 gallons
- US fuel economy is miles per gallon
Precision
The factor 0.0625 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.
Watch Out For
- A US cup is 237 mL, a metric cup 250 mL and a Japanese cup 200 mL. Baking by volume is why the same recipe fails in another country.
- The UK imperial gallon is 4.546 litres — 20% larger. A "gallon" without a country attached is ambiguous, and US MPG figures look worse when read as imperial.
In Code
`javascript
const cupToGallon = (value) => value * 0.0625;
``
Where This Conversion Comes Up
- Cooking
- Chemistry
- Fuel
- Beverages
- Medicine
How Many Decimals Do You Need?
Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 cup with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 cup becomes | Error |
|---|---|---|---|
| 0 | 0 | 0 | 100.0000% |
| 1 | 0.1 | 13.7 | 60.0000% |
| 2 | 0.06 | 8.22 | 4.0000% |
| 3 | 0.063 | 8.631 | 0.8000% |
| 4 | 0.0625 | 8.5625 | — |
The right number of significant figures is set by your input, not by the converter. If you measured cups to three significant figures, the answer in gallons is only good to three — writing more digits claims precision the measurement never had.