Convert US gallons to Imperial fluid ounces
1 US gallon is 133.23 fl oz (UK). One US gallon is exactly 133.227869541 imperial fluid ounces.
One US gallon is 133.22787 imperial fluid ounces. To convert US gallons to imperial fluid ounces, multiply by 133.22787; to go the other way, divide by 133.22787 or multiply by 0.007505937. The relation is exact but the figure is not: it is a rounding of a number that does not terminate, and it follows from NIST Handbook 130. Exactly 231 cubic inches.
Factor checked against the defining standard · How we check
- US gallons × 133.22787
1 * 133.22787133.228 fl oz (UK)
1 US gallon in every volume unit
| Unit | Value | Exact factor |
|---|---|---|
| US teaspoons | 768 tsp | × 768 |
| US tablespoons | 256 tbsp | × 256 |
| US fluid ounces | 128 fl oz | × 128 |
| US cups | 16 cup | × 16 |
| US pints | 8 pt | × 8 |
| US quarts | 4 qt | × 4 |
| US gallons (as entered) | 1 gal | — |
| milliliters | 3,785.411784 ml | × 3,785.411784 |
| liters | 3.785411784 L | × 3.785411784 |
| imperial gallons | 0.8326741846 gal (UK) | × 0.832674184629 |
| imperial quarts | 3.330696739 qt (UK) | × 3.33069673852 |
| imperial pints | 6.661393477 pt (UK) | × 6.66139347703 |
| imperial fluid ounces | 133.2278695 fl oz (UK) | × 133.227869541 |
| imperial gills | 26.64557391 gi (UK) | × 26.6455739081 |
| cubic millimetres | 3,785,411.784 mm³ | × 3,785,411.784 |
| cubic centimetres | 3,785.411784 cm³ | × 3,785.411784 |
| cubic inches | 231 in³ | × 231 |
| cubic feet | 0.1336805556 ft³ | × 0.133680555556 |
| cubic yards | 0.004951131687 yd³ | × 0.00495113168724 |
| cubic metres | 0.003785411784 m³ | × 0.003785411784 |
Factors are entered by hand from NIST Handbook 130 rather than derived from a units library, so the ones that terminate are exact rather than rounded.
How do you convert US gallons to imperial fluid ounces? The converter and the working
- 1.Take the measurement in US gallons.
- 2.Multiply by 133.22787 — that is how many imperial fluid ounces fit in one US gallon.
- 3.To go back the other way, divide by 133.22787, or multiply by 0.007505937.
Worked example: 25 US gallons to imperial fluid ounces
- Formula
- gal × 133.22787 = fl oz (UK)
- Arithmetic
- 25 × 133.22787 = 3,330.7 fl oz (UK)
- Answer
- 25 gal = 3,330.7 fl oz (UK)
The factor is rounded for display; the figure above is computed from the full value.
US gallons to imperial fluid ounces conversion table
| US gallons | Imperial fluid ounces |
|---|---|
| 1 gal | 133.23 fl oz (UK) |
| 2 gal | 266.46 fl oz (UK) |
| 3 gal | 399.68 fl oz (UK) |
| 4 gal | 532.91 fl oz (UK) |
| 5 gal | 666.14 fl oz (UK) |
| 6 gal | 799.37 fl oz (UK) |
| 7 gal | 932.6 fl oz (UK) |
| 8 gal | 1,065.82 fl oz (UK) |
| 9 gal | 1,199.05 fl oz (UK) |
| 10 gal | 1,332.28 fl oz (UK) |
| 12 gal | 1,598.73 fl oz (UK) |
| 15 gal | 1,998.42 fl oz (UK) |
| 20 gal | 2,664.56 fl oz (UK) |
| 25 gal | 3,330.7 fl oz (UK) |
| 50 gal | 6,661.39 fl oz (UK) |
| 100 gal | 13,322.79 fl oz (UK) |
| 200 gal | 26,645.57 fl oz (UK) |
| 300 gal | 39,968.36 fl oz (UK) |
| 500 gal | 66,613.93 fl oz (UK) |
| 1000 gal | 133,227.87 fl oz (UK) |
| 2000 gal | 266,455.74 fl oz (UK) |
| 5000 gal | 666,139.35 fl oz (UK) |
| 10000 gal | 1,332,278.7 fl oz (UK) |
What is a US gallon?
Exactly 231 cubic inches. The imperial gallon is 4.546 liters, so US and UK fuel economy figures are not comparable.
What is an imperial fluid ounce?
One 160th of an imperial gallon, 28.4130625 ml exactly. The US fluid ounce is one 128th of a smaller gallon at 29.57 ml, so the two ounces differ by about 4% in the opposite direction to the gallons.
How many imperial fluid ounces are in a US gallon?
One US gallon is 133.22787 imperial fluid ounces. Going the other way, one imperial fluid ounce is 0.007505937 US gallons. Both figures come from the same defined relation rather than from a measurement, which is why they are the same today as they were in 1959.
Every volume unit here
The whole group — 20 units with their symbols and the size of each one in liters — is on the conversion index, along with every pair it makes. The table above already gives each of them relative to a US gallon.
Cite this page
- APA
- Rule Calculator. (2026). Convert US gallons to imperial fluid ounces. Rule Calculator. https://rulecalculators.com/convert/gallon-to-imperial-fluid-ounce
- MLA
- "Convert US gallons to imperial fluid ounces." Rule Calculator, August 16, 2026, https://rulecalculators.com/convert/gallon-to-imperial-fluid-ounce.
- Chicago
- Rule Calculator. "Convert US gallons to imperial fluid ounces." Rule Calculator. Last reviewed August 16, 2026. https://rulecalculators.com/convert/gallon-to-imperial-fluid-ounce.
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Questions people actually ask
- How many imperial fluid ounces are in a US gallon?
- 133.22787. One 160th of an imperial gallon, 28.4130625 ml exactly. The US fluid ounce is one 128th of a smaller gallon at 29.57 ml, so the two ounces differ by about 4% in the opposite direction to the gallons.
- How do I convert imperial fluid ounces back to US gallons?
- Divide by 133.22787, or multiply by 0.007505937 — they are the same operation.
Other volume conversions
Imperial fluid ounces to US gallons — the same conversion the other way.