Converters
12
US gallons to US fluid ounces Converter
Convert us gallons to us fluid ounces instantly with the formula, worked examples, rounding guidance, and related volume conversions.
Units
85
Mode
Live
Pair-specific conversion guide
US gallon to US fluid ounce formula
Converting US gallons to US fluid ounces is straightforward: one US gallon equals exactly 128 US fluid ounces. This conversion is commonly used for measuring liquids in cooking, automotive fluids, and household products. To convert, multiply the number of gallons by 128 to get the equivalent in fluid ounces.
Formula model
1 gal = 128 fl oz
1 US gallon equals
Quick factor: 1 gal = 128 fl oz.
For quick mental math, remember that 1 gallon equals 128 ounces, so 2 gallons equal 256 ounces, and so on.
When measuring liquids, use a liquid measuring cup marked in fluid ounces for accuracy, especially for smaller amounts.
Check the measurement system for cooking units: US customary and imperial volumes are not always the same.
Precision and rounding
The calculation uses the catalog's fixed conversion factors between gal and fl oz. Full decimal precision is kept for the calculation; only the displayed value is rounded for readability.
Reference: NIST conversion factorsVolume
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Conversion table
1 US gallon equals
| Unit | Value |
|---|---|
| Liter L | 3.785411784 |
| Milliliter mL | 3785.411784 |
| Cubic meter m3 | 0.003785411784 |
| US teaspoon tsp | 768 |
| US tablespoon tbsp | 256 |
| US fluid ounce fl oz | 128 |
| US cup cup | 16 |
| US pint pt | 8 |
| US quart qt | 4 |
FAQ
US gallon to US fluid ounce questions
How many US fluid ounces are in 5 US gallons?
There are 640 US fluid ounces in 5 US gallons, since 5 multiplied by 128 equals 640.
Is the US fluid ounce the same as the imperial fluid ounce?
No, the US fluid ounce is slightly larger than the imperial fluid ounce. One US gallon equals 128 US fluid ounces, while one imperial gallon equals 160 imperial fluid ounces.