Fluid Ounces to Gallons (fl oz to gal)

How to convert fluid ounces to gallons

Divide the fluid ounces by 128:

gallons = fluid ounces ÷ 128

100 fl oz ÷ 128 = 0.78125 gal. Because 128 is a power of two, common amounts come out as tidy fractions: 32 fl oz is 1/4 gallon, 64 fl oz is 1/2, 96 fl oz is 3/4. To go the other way, multiply gallons by 128 — the gallons to ounces converter also counts bottles per gallon.

Ounces to gallons chart

Adding up a day of drinks

Bottles and cups come in different sizes, so add the fluid ounces first and convert the total. Open Convert a list of values, paste each amount on its own line — 16.9, 12, 20, 8 — and download the list; the column of gallons adds up to the day’s total. For example:

• 3 bottles of 16.9 fl oz + 2 cans of 12 fl oz = 74.7 fl oz = 0.58 gallon;
• 4 bottles of 20 fl oz = 80 fl oz = 0.625 gallon.

How many bottles make a gallon

Water bottles are sold in fluid ounces, and a gallon is a common daily target, so the useful question is how many bottles fill it. Divide 128 by the bottle size:

A 16.9 fl oz bottle is a 500 mL bottle, so eight of them make 4 liters, a little more than a gallon (3.785 L).

Ounces, quarts and gallons

The result lists quarts and liters too: a quart is 32 fl oz and a quarter of a gallon; a liter is 33.8 fl oz, slightly more than a quart. For metric amounts, see ounces to milliliters or gallons to liters; for kitchen measures, ounces to cups.

A British recipe or a UK fuel figure uses the imperial gallon of 160 imperial fluid ounces (4.546 L), about 20% larger than the U.S. gallon. The imperial fluid ounce is also slightly smaller (28.4 mL against 29.6 mL). This page uses U.S. units throughout; for imperial gallons, use the switch on gallons to ounces.