Ounces to Gallons (oz to gal)

Divide the US fluid ounces by 128. A total like 100 fl oz gives 0.7813 gallon, just over three quarters of a gallon, and 160 fl oz gives 1.25 gallons.

When the total runs past a gallon, split off the whole gallons first. 300 fl oz contain two full gallons with 44 fl oz left over, which is 2.344 gallons in all.

Check the label before you divide. Fluid ounces are marked fl oz, while a net weight in ounces describes how heavy the food is, and the gallon figure for that depends on the food.

British recipes and labels use the imperial fluid ounce, and it takes 160 of those to fill an imperial gallon. So the divisor depends on the country: 128 for American amounts and 160 for British ones.

Mixing the two skews the result. A full US gallon fills only 0.8327 of an imperial gallon, and a British gallon of 160 imp fl oz equals 1.201 US gallons.

To total a stack of containers, multiply the size by the count, then divide by 128. A case of cans works like this: 24 × 12 fl oz = 288 fl oz, or 2.25 gallons.

Water bottles follow the same pattern. A pack of eight bottles adds up to 8 × 16.9 fl oz = 135.2 fl oz, which is 1.056 gallons. Refill a bottle of 24 fl oz five times in a day and you have poured 5 × 24 fl oz = 120 fl oz, or 0.9375 gallon.

To find how many bottles fill a gallon, divide the other way. A gallon takes 7.6 bottles of 16.9 fl oz, or 5.3 refills of a bottle that holds 24 fl oz. For totals under a gallon, ounces to quarts often gives a rounder number.