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1 Gallon to Fluid Ounces

1 gallon is 128 fluid ounces. See the step-by-step breakdown and reference table below, or try a different value in the calculator.

1 gal = 128 fl oz
gal × 128 = fl oz
Try: 2 gal to fl oz 6 gal to fl oz
1 gal is also
1 gal = 3.79 L 1 gal = 3,785.41 mL 1 gal = 16 cup 1 gal = 8 pt 1 gal = 4 qt 1 gal = 256 tbsp 1 gal = 768 tsp
gal
128 fl oz

Formula and Step-by-Step

gal × 128 = fl oz
  1. Start with 1 gal
  2. Multiply by 128: 1 × 128 = 128
  3. Result: 1 gal = 128 fl oz

Since 1 gallon equals 128 fluid ounces, multiply any gallon value by 128 to convert.

Other Gallon to Fluid Ounce Values

Gallons (gal) Fluid Ounces (fl oz)
1 gal 128 fl oz
2 gal 256 fl oz
5 gal 640 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
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
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Frequently Asked Questions

1 gallon equals 128 fluid ounces.
The formula is: gal × 128 = fl oz. See the gal to fl oz formula page for worked examples.
Use the fluid ounces to gallon converter. The reverse formula is: fl oz ÷ 128 = gal.
The calculator uses the full-precision conversion factor for accuracy. Table values and displayed results are rounded for readability.
The conversion formula (gal × 128 = fl oz) is based on internationally defined standards. Displayed results are rounded for readability, while the calculator uses the full-precision factor.
person Written by Sean Day verified Reviewed by UnitCompare update Last updated Mar 28, 2026