How to Convert US fluid ounces to US gallons (fl oz to gal)
Volume conversions help with baking from American recipes, comparing petrol prices quoted per gallon abroad with pump prices per litre here, and reading PUB water bills in cubic metres. This guide shows how to convert us fluid ounces into us gallons by hand, with examples and a quick-reference table.
The conversion
To convert us fluid ounces to us gallons, multiply the value by 0.0078124959. To go the other way, divide by the same number (or multiply by 128.0000676281). For a quick estimate, multiply by about 0.0078.
US gallons = us fluid ounces × 0.0078124959
Worked examples
- 3 fl oz = 0.023437 gal
- 12.5 fl oz = 0.097656 gal
- 75 fl oz = 0.585937 gal
US fluid ounces to US gallons table
| US fluid ounces | US gallons |
|---|---|
| 1 fl oz | 0.007812 gal |
| 2 fl oz | 0.015625 gal |
| 5 fl oz | 0.039062 gal |
| 10 fl oz | 0.078125 gal |
| 20 fl oz | 0.15625 gal |
| 25 fl oz | 0.195312 gal |
| 50 fl oz | 0.390625 gal |
| 100 fl oz | 0.78125 gal |
| 250 fl oz | 1.9531 gal |
| 500 fl oz | 3.9062 gal |
| 1,000 fl oz | 7.8125 gal |
Common questions
Is fl oz to gal exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the US gallons to US fluid ounces converter.
Mistakes to avoid
Multiplying when you should divide
Converting to a smaller unit gives a bigger number, and converting to a larger unit gives a smaller one. If your answer moves the wrong way, you have inverted the factor.
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
Background
Many conversion factors are exact by definition. The inch has been defined as exactly 2.54 centimetres since 1959, and the pound as exactly 0.45359237 kilograms, so conversions involving them can be as precise as you need.
Singapore adopted the metric system in the 1970s, replacing imperial units and traditional Chinese measures in most official uses. Metric units are now standard in schools, trade and government, but older units survive in property, markets and imported goods.
Writing the units next to every number while you work is the simplest way to avoid mistakes. If the units do not cancel to leave the one you want, the calculation is set up wrongly.
For any value, use the US fluid ounces to US gallons Converter or browse all volume converters.
Run your own numbers: US fluid ounces to US gallons Converter