swap_horiz Need fluid ounces to gallons instead?

5 Gallons to Fluid Ounces

5 gallons equals 640 fluid ounces using the gal to fl oz formula. Scroll down for the full calculation.

5 gal = 640 fl oz
gal × 128 = fl oz
Try: 4 gal to fl oz 6 gal to fl oz 10 gal to fl oz
5 gal is also
5 gal = 18.93 L 5 gal = 18,927.06 mL 5 gal = 80 cup 5 gal = 40 pt 5 gal = 20 qt 5 gal = 1,280 tbsp 5 gal = 3,840 tsp
gal
640 fl oz

Step-by-Step Calculation

gal × 128 = fl oz
  1. Start with 5 gal
  2. Multiply by 128: 5 × 128 = 640
  3. Result: 5 gal = 640 fl oz

This conversion factor (128) is the same for every gallon to fluid ounce calculation.

Gallon to Fluid Ounce Conversion Table

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
calculate Gallon to Fluid Ounce Converter swap_horiz Fluid Ounce to Gallon Converter functions Gallon to Fluid Ounce Formula water_drop All Volume / Capacity Conversions

Frequently Asked Questions

5 gallons equals 640 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 gallons 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