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1 US gal ≈ 128 US fl oz.
Formula and calculation
US fl oz = US gal × 128
Substituting 1 US gal gives approximately 128 US fl oz. Definitions use the constants above; arithmetic uses browser floating point and displays at most 12 significant digits. The rounded table is not an instrument calibration or certified measurement.
Which units does this page use?
US gallons: US liquid gallon: 231 cubic inches, not the imperial gallon.
US fluid ounces: US liquid fluid ounce, not the imperial fluid ounce or mass ounce.
When this direction is useful
Start here when your source record uses US gal for US liquid-container capacities, but the receiving specification is expressed in US fl oz for US drink and liquid product volumes. Enter the original quantity rather than reusing a previously rounded result. If your source uses US fl oz, use the reverse converter instead.
Conversion table
| US gallons (US gal) | US fluid ounces (US fl oz) |
|---|---|
| 0 | 0 |
| 1 | 128 |
| 5 | 640 |
| 10 | 1280 |
| 100 | 12800 |
Limits and interpretation
These are non-negative physical quantities; negative inputs are rejected. Converting a unit changes neither the measured object nor the original precision. Use a decimal dot; grouping commas are not accepted. No external rates, live data or account are involved.
Frequently asked questions
Can I convert the other way?
Yes. Convert US fluid ounces to US gallons with the inverse equation. Rounding a result before converting it back can introduce a small difference.
Are these the same as every similarly named unit?
No. Check the two definitions above. International length, avoirdupois mass, US customary liquid measures and temperature readings are explicitly distinguished; an ambiguous label on a source document must be resolved first.
Where do the conversion definitions come from?
They use SI and defined customary conversion relationships. See the NIST Guide for the Use of SI. Output formatting is this tool's display policy, not extra measurement accuracy.