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Convert US gallons to fluid ounces. Chart, formula, and reverse direction.
A US gallon (gal) equals exactly 128 US fluid ounces (fl oz). To convert gallons to fl oz, multiply by 128; to convert fl oz to gallons, divide by 128.
1 gal equals 128.00 fl oz.
| US Gallons (gal) | Fluid Ounces (fl oz) |
|---|---|
| 0.25 gal | 32.000 fl oz |
| 0.5 gal | 64.000 fl oz |
| 0.75 gal | 96.000 fl oz |
| 1 gal | 128.00 fl oz |
| 1.5 gal | 192.00 fl oz |
| 2 gal | 256.00 fl oz |
| 2.5 gal | 320.00 fl oz |
| 3 gal | 384.00 fl oz |
| 4 gal | 512.00 fl oz |
| 5 gal | 640.00 fl oz |
| 6 gal | 768.00 fl oz |
| 7 gal | 896.00 fl oz |
| 8 gal | 1024.00 fl oz |
| 10 gal | 1280.00 fl oz |
| 15 gal | 1920.00 fl oz |
| 20 gal | 2560.00 fl oz |
| 25 gal | 3200.00 fl oz |
| 50 gal | 6400.00 fl oz |
| 100 gal | 12800.00 fl oz |
Chart values use the exact US relationship 1 gallon = 128 fl oz. UK Imperial gallons hold 160 UK fl oz.
Formula
fl oz = gal × 128 | gal = fl oz ÷ 128gal = US liquid gallon — US volume unit (1 gal = 128 fl oz = 3.7854 L)
fl oz = US fluid ounce — US volume unit (1 fl oz = 29.5735 mL)
Worked Example
Convert 5 gallons to fluid ounces
Did you know? The US gallon is based on the British 'wine gallon' of 1707 (231 cubic inches). When the UK adopted the larger imperial gallon in 1824, the US kept the older one — which is why US milk jugs and gas gallons are smaller than their UK equivalents.
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