US gallon to US fluid ounce Converter
Type a value — the answer appears instantly. 1 gal = 128 fl oz.
Reviewed by the OmniCalc teamMethod verified 2026-07-01
128 US fluid ounces
= 3.78541 L= 3,785.41 ml
equals 128 US fluid ouncesFormula: fl oz = gal × 128
US gallon to US fluid ounce formula
fl oz = gal × 128
Convert 5 US gallons to US fluid ounces
- Start with 5 US gallons.
- Multiply by the conversion factor: 5 × 128 = 640.
- So 5 gal = 640 fl oz.
US gallon to US fluid ounce conversion table
| US gallons (gal) | US fluid ounces (fl oz) |
|---|---|
| 0.01 gal | 1.28 fl oz |
| 0.1 gal | 12.8 fl oz |
| 0.25 gal | 32 fl oz |
| 0.5 gal | 64 fl oz |
| 1 gal | 128 fl oz |
| 2 gal | 256 fl oz |
| 3 gal | 384 fl oz |
| 4 gal | 512 fl oz |
| 5 gal | 640 fl oz |
| 6 gal | 768 fl oz |
| 7 gal | 896 fl oz |
| 8 gal | 1,024 fl oz |
| 9 gal | 1,152 fl oz |
| 10 gal | 1,280 fl oz |
| 15 gal | 1,920 fl oz |
| 20 gal | 2,560 fl oz |
| 25 gal | 3,200 fl oz |
| 30 gal | 3,840 fl oz |
| 40 gal | 5,120 fl oz |
| 50 gal | 6,400 fl oz |
| 75 gal | 9,600 fl oz |
| 100 gal | 12,800 fl oz |
| 250 gal | 32,000 fl oz |
| 500 gal | 64,000 fl oz |
| 1,000 gal | 128,000 fl oz |
| 5,000 gal | 640,000 fl oz |
| 10,000 gal | 1,280,000 fl oz |
Unit definitions
What is a US gallon?
The US gallon is defined as exactly 231 cubic inches, or 3.785411784 litres. It is the standard unit for fuel, milk, and large liquid quantities in the United States. It is about 20% smaller than the imperial gallon.
What is a US fluid ounce?
The US fluid ounce is one 128th of a US gallon, about 29.57 millilitres. It is the customary unit for beverages and liquid packaging in the United States. It is slightly larger than the imperial (UK) fluid ounce.
Frequently asked questions
How many US fluid ounces are in one US gallon?
One US gallon equals 128 US fluid ounces (1 gal = 128 fl oz).
How do I convert US gallons to US fluid ounces?
Multiply the value in US gallons by 128. For example, 10 gal × 128 = 1,280 fl oz.
Which is bigger — a US gallon or a US fluid ounce?
A US gallon is bigger: one US gallon contains 128 US fluid ounces.
Is this US gallon to US fluid ounce converter free?
Yes — the converter is free, works offline once loaded, and computes instantly in your browser without sending your numbers to a server.
Conversion factors follow international definitions (SI / NIST). Last verified 2026-07-01.