US Gallons to US Fluid Ounces Converter

Convert US gallons to US fluid ounces instantly. Both are US customary units, and the relationship is exact: there are 128 US fluid ounces in every US gallon, so to go from US gallons (gal) to US fluid ounces (fl oz) you multiply by 128 — for example, 1 gal = 128 fl oz and 0.5 gal = 64 fl oz. This converter defaults to…

128

1 US gallon = 128 US fluid ounce  ·  1 US gallon = 128 US fluid ounce

1 US gallon IN EVERY UNIT

METRIC

US CUSTOMARY

IMPERIAL / UK

SPOONS & COOKING MEASURES

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HOW TO USE

  1. 1

    Enter the volume in US gallons (gal) in the value box — the converter defaults to US gallons → US fluid ounces.

  2. 2

    Read the US fluid ounce (fl oz) result instantly, or do it by hand: multiply the gallons by 128.

  3. 3

    Use the gallons-to-fl-oz table below for common values, or tap ⇄ to convert US fluid ounces back to US gallons.

  4. 4

    Need another unit? Pick any of the 59 volume units in the dropdown, then Share or Embed your conversion.

QUICK REFERENCE

1 US cup

236.6 mL

1 metric cup

250 mL

1 imp cup

284.1 mL

1 US tbsp

14.79 mL

1 US tsp

4.929 mL

1 metric tbsp

15 mL

1 AU tbsp

20 mL

1 US cup

16 US tbsp

1 US tbsp

3 US tsp

1 stick

½ US cup

ABOUT COOKING VOLUME UNITS

Recipe measurements look simple until you notice that a “cup” or “tablespoon” means different things in different countries — which is exactly what trips cooks up. A US cup is 236.6 mL, but a metric cup (used in Australia, New Zealand and much of the world) is 250 mL, and an old imperial (UK) cup is 284 mL; US nutrition labels even use a 240 mL “legal cup”. Spoons vary too: a US tablespoon is 14.8 mL and a metric one is 15 mL — close enough to ignore — but an Australian tablespoon is 20 mL, equal to four teaspoons rather than three, which is a genuine trap when following an Aussie recipe. Fluid ounces differ as well: the US fluid ounce is 29.57 mL while the imperial one is 28.41 mL, so US and UK pints, quarts and gallons are not the same size. This converter keeps every national version separate and also handles the small “old recipe” measures — a dash is an eighth of a teaspoon, a pinch a sixteenth and a smidgen a thirty-second — plus the US stick of butter, which is half a cup or eight tablespoons. One thing it does not do is turn cups into grams: that depends on the ingredient, because a cup of flour and a cup of sugar weigh different amounts. Every unit here is stored as its exact number of millilitres, so any conversion is just the input turned into millilitres and then into the unit you want.

FREQUENTLY ASKED QUESTIONS

Multiply the number of US gallons by 128. Because there are exactly 128 US fluid ounces in a US gallon, multiplying by 128 gives the fluid-ounce value. For example, 3 gal × 128 = 384 fl oz. The converter does this instantly for any value.

  • Formula: US fl oz = US gallons × 128.
  • There are exactly 128 US fl oz in a US gallon.
  • 3 gal = 384 fl oz; 0.5 gal = 64 fl oz.
  • To reverse it, divide fluid ounces by 128.

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Last updated: · 30 cooking-volume units · Metric, US customary, imperial & special measures, all national cup/spoon sizes kept separate · Verified by the EagleCalculator team · Eagle-eyed accuracy for every calculation.