At One Place

US gallons to US fluid ounces

1 US gallon in US fluid ounces
1 gal = 128 fl oz
fl oz = gal × 128

To convert US gallons to US fluid ounces, multiply by 128. The table below gives the values people look up most often, and the converter works for any number.

US gallons to US fluid ounces table

Common US gallon values converted to US fluid ounces.
US gallons US fluid ounces
1 gal 128
2 gal 256
3 gal 384
4 gal 512
5 gal 640
10 gal 1,280
15 gal 1,920
20 gal 2,560
25 gal 3,200
30 gal 3,840
40 gal 5,120
50 gal 6,400
75 gal 9,600
100 gal 12,800
250 gal 32,000
500 gal 64,000
1,000 gal 128,000

How the conversion works

The relationship is fl oz = gal × 128. Both units measure volume, so the conversion is a fixed factor that never changes. The figure is exact rather than approximate: since the international yard and pound agreement of 1959, an inch is defined as exactly 25.4 millimetres and a pound as exactly 0.45359237 kilograms, and every other imperial and US customary unit here is derived from those two.

US gallon: US liquid gallon. The imperial gallon is about 20% larger.

Common questions

How many US fluid ounces are in one US gallon?
One US gallon equals 128 US fluid ounces. fl oz = gal × 128.
How do you convert US gallons to US fluid ounces?
Use fl oz = gal × 128. So 10 gal is 1,280 fl oz.
How many US gallons are in one US fluid ounce?
One US fluid ounce equals 0.0078125 US gallons, which is the reverse of the conversion above.
Is there more than one kind of US gallon?
US liquid gallon. The imperial gallon is about 20% larger.

Related pages

Sources

  1. Guide for the Use of the International System of Units (SP 811) — NIST (Public domain (US Government))
  2. The International System of Units (SI Brochure) — Bureau International des Poids et Mesures
  3. Calculated on this page — At One Place

How these figures are compiled and checked