pakmath.com

US Gallons to US Fluid Ounces (gal to fl oz) Converter

1 US gallon (gal) = 128 US fluid ounces (fl oz). To convert US gallons to US fluid ounces, multiply by 128: 15 gal × 128 = 1,920 fl oz.

1 gal = 127.9999998377 fl oz
Convert the other way: US Fluid Ounces to US Gallons

Quick facts

How to convert US gallons to US fluid ounces

  1. Take the value in US gallons.
  2. Multiply it by 128 (the number of US fluid ounces in one US gallon).
  3. Round the result to the precision you need.
fl oz = gal × 128

Worked example (a car fuel tank): 15 gal × 128 = 1920 fl oz.

To convert US fluid ounces back to US gallons, multiply by 0.0078125, or divide by 128.

Source: NIST Handbook 44, Appendix C, and NIST SP 811 (US customary volume units).

US Gallons to US Fluid Ounces conversion table

US Gallons to US Fluid Ounces conversion table
US Gallons [gal]US Fluid Ounces [fl oz]
0.01 gal1.2799999984 fl oz
0.1 gal12.7999999838 fl oz
1 gal127.9999998377 fl oz
2 gal255.9999996754 fl oz
3 gal383.9999995131 fl oz
5 gal639.9999991885 fl oz
10 gal1279.9999983769 fl oz
20 gal2559.9999967539 fl oz
50 gal6399.9999918846 fl oz
100 gal12799.9999837693 fl oz
1000 gal127999.9998376927 fl oz

gal to fl oz chart from 1 to 100

US Fluid Ounces to US Gallons conversion table

US Fluid Ounces to US Gallons conversion table
US Fluid Ounces [fl oz]US Gallons [gal]
0.01 fl oz0.000078125 gal
0.1 fl oz0.00078125 gal
1 fl oz0.0078125 gal
2 fl oz0.015625 gal
3 fl oz0.0234375 gal
5 fl oz0.0390625 gal
10 fl oz0.0781250001 gal
20 fl oz0.1562500002 gal
50 fl oz0.3906250005 gal
100 fl oz0.781250001 gal
1000 fl oz7.8125000099 gal

US Gallons vs US Fluid Ounces

US GallonUS Fluid Ounce
Symbolgalfl oz
Equals1 gal = 128 fl oz1 fl oz = 0.0078125 gal

What is a US gallon?

A US customary unit equal to 4 quarts. Used in the US for fuel, milk, and paint.

What is a US fluid ounce?

A US customary unit equal to 1/16 of a US pint. Used in the US for beverage and bottle sizes.

Frequently asked questions

How many US fluid ounces are in a US gallon?

There are 128 US fluid ounces in 1 US gallon (1 gal = 127.9999998377 fl oz).

How many US gallons are in a US fluid ounce?

There are 0.0078125 US gallons in 1 US fluid ounce (1 fl oz = 0.0078125 gal).

How do I convert US gallons to US fluid ounces?

Multiply the number of US gallons by 128. For example, 10 gal × 128 = 1,280 fl oz. To convert back, multiply by 0.0078125.

What is 10 gal in US fluid ounces?

10 gal = 1,280 fl oz.

What is 100 gal in US fluid ounces?

100 gal = 12,800 fl oz.

Is the conversion exact?

Yes. The factor comes from the official definitions of both units (NIST Handbook 44, Appendix C, and NIST SP 811 (US customary volume units)). Results are shown to up to 10 decimal places; round them to suit your purpose.

Popular volume conversions

Convert US gallons to other units

Convert other units to US fluid ounces

Open the full volume converter with every unit →

Related converters

Reviewed by

Dr. Muhammad Amjad Khadim PhD Mathematics

Dr. Muhammad Amjad Khadim holds a PhD in Mathematics. He writes and reviews the guides on pakmath.com and checks every formula, conversion factor and worked example against published standards and official guidance before it goes live. Spotted an error? Tell us and it will be corrected.

Google Scholar profile (opens in a new tab)

First published 28 October 2026 · Last reviewed 5 November 2026