Convert US gallons to fluid ounces
1 US gallon equals 128 fluid ounces. Type any number below — the other side updates instantly.
US gallons to fluid ounces — quick reference
| US gallons | fluid ounces |
|---|---|
| 0.25 gal | 32 fl oz |
| 0.5 gal | 64 fl oz |
| 1 gal | 128 fl oz |
| 1.5 gal | 192 fl oz |
| 2 gal | 256 fl oz |
| 3 gal | 384 fl oz |
| 4 gal | 512 fl oz |
| 5 gal | 640 fl oz |
| 10 gal | 1280.001 fl oz |
| 20 gal | 2560.001 fl oz |
How to convert
Multiply the number of US gallons by 128 to get fluid ounces. To go the other way, multiply fluid ounces by 0.007812 to get US gallons. The conversion factor is fixed and exact, so you can use this on any value.
About these units
US gallons
- Definition
- A US gallon equals 128 fluid ounces, 4 quarts, or about 3.785 liters. The Imperial (UK) gallon is larger at 4.546 L.
- History
- The US gallon descends from the British wine gallon of 1707; the UK redefined its own gallon in 1824, creating the divergence that persists today.
- Current use
- The US gallon is used in the United States for fuel, milk, paint, and large-volume liquids. The Imperial gallon survives in some contexts in the UK and Caribbean.
Fluid ounces
- Definition
- A US fluid ounce (symbol: fl oz) equals about 29.57 ml. There are 16 fl oz in a US pint and 128 in a US gallon.
- History
- The US fluid ounce was set by Congress in 1832. The Imperial fluid ounce (used in the UK) is slightly different at about 28.41 ml.
- Current use
- Used in the US for liquid measurements — beverages, recipes, cosmetics — and shown on most US food and drink labels.
Frequently asked
- How many fluid ounces are in 1 US gallon?
- 1 US gallon = 128 fluid ounces.
- How do you convert US gallons to fluid ounces?
- Multiply the number of US gallons by 128 to get fluid ounces. To go the other way, multiply fluid ounces by 0.007812 to get US gallons. The conversion factor is fixed and exact, so you can use this on any value.
- What is 3 US gallons in fluid ounces?
- 3 US gallons = 384 fluid ounces.
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