Cups in a gallon: why the answer is 16

That is the US liquid gallon measured in US customary cups of 8 fluid ounces: 128 fl oz divided by 8 is 16. A half gallon holds 8 cups, a quart holds 4 and a pint holds 2. Water and milk give the same count, because cups and gallons measure volume.

Enter gallons to get cups, or switch From to Cups to get gallons. Pick a cup size if your recipe uses the 240 mL US nutrition label cup, the 250 mL metric cup or the Imperial cup. The tables below give pints, quarts, fluid ounces and liters.

Quick answer: how many cups are in a gallon?

There are 16 cups in a US liquid gallon. A gallon is 128 fluid ounces and a US cup is 8, so 128 / 8 = 16. A half gallon holds 8 cups, a quart 4 and a pint 2. Multiply gallons by 16 to get cups: a 5 gallon bucket holds 80 cups.

Key takeaways

• 1 US gallon = 16 cups = 8 pints = 4 quarts = 128 fl oz.
• Water and milk give the same count, because cups and gallons both measure volume.
• The Imperial gallon is about 20 percent larger: 4.54609 L against 3.785412 L for the US gallon.
• An Imperial gallon holds about 19.22 US cups.

Worked example: cups in a gallon by hand

Start from the gallon chain in NIST Handbook 44: 1 gallon = 4 quarts = 8 pints = 16 cups = 128 fl oz. Each step is a plain multiplication.

1. Gallons to cups: multiply by 16. A 5 gallon bucket holds 5 x 16 = 80 cups.
2. Cups to gallons: divide by 16. A pot of 12 cups holds 12 / 16 = 0.75 gallons, which is 3 quarts.
3. Half gallon: 128 fl oz / 2 = 64 fl oz, and 64 / 8 = 8 cups.
4. Quart: 4 quarts fill a gallon, so one quart is 16 / 4 = 4 cups.
5. Liters: a US cup is 236.588 mL, so one liter holds 1,000 / 236.588 = 4.2268 cups, and a gallon holds 3.785 liters.

Rounding: the math uses the exact US units, with the gallon at 231 cubic inches. The cup figure shows the nearest kitchen fraction in eighths or thirds when one is within 3 percent, else two decimals, so 1/10 of a gallon (1.6 cups) shows as 1 5/8 cups. Just past 2 gallons the nearest fraction would be 32 cups, the end of the rule, so the figure keeps two decimals there: 2.003 gallons shows as 32.05 cups. Gallons show up to two decimals, or up to four under 0.1 gallon, so 12 cups shows as 0.75 gal and 1 cup as 0.0625 gal.

How many 8 oz cups are in a gallon of water?

Sixteen. A US gallon is 128 fl oz, and an 8 oz cup is one sixteenth of that. The count is the same for a gallon of milk or any other liquid, because cups and gallons measure volume. Weight is a separate question: USDA FoodData Central lists 8 fl oz of water, one cup, at 237 g (read 8 October 2026), and milk, oil and honey each have their own USDA cup weights. Our grams to cups converter covers those. If you are counting 16 oz glasses instead, the answer is 8, and the table above covers the other common sizes.

Is 1 gallon equal to 4 cups?

No. Four cups make one quart, and four quarts make one gallon, so a gallon is 16 cups. Quarts and gallons share the "four" step, which is an easy place to slip: 4 cups in a quart, 4 quarts in a gallon. Four cups of milk is one quart, which is a quarter of a gallon. A half gallon of milk is 8 cups, so a half gallon carton pours eight 8 oz servings. If you have 2 cups, that is one pint, or one eighth of a gallon.

How many cups are in 5 gallons, or a fifth of a gallon?

Multiply by 16 either way. Five gallons is 80 cups, which is also 20 quarts or 640 fl oz. A fifth of a gallon is 16 / 5 = 3.2 cups, or 25.6 fl oz. A tenth of a gallon is 1.6 cups, or 12.8 fl oz. Five gallons also holds ten half gallons, since each half gallon is 8 cups and 80 / 8 = 10. The first table gives every one of these rows in pints, quarts and liters too, so you can read the whole chain at once.

Is a UK (Imperial) gallon the same as a US gallon?

No. NIST lists the Imperial gallon at 4.54609 L and the US gallon at 3.785412 L, so the Imperial gallon is about 20 percent larger. Each system still has 16 of its own cups in its own gallon. The Imperial cup is 10 Imperial fl oz (284.131 mL), and 16 of them fill the 160 fl oz Imperial gallon. The trouble starts when you mix systems. An Imperial gallon holds about 19.22 US cups. A US gallon holds about 13.32 Imperial cups, so a UK recipe measured with US cups comes out about a sixth short of an Imperial gallon.

The US nutrition label cup is the 240 mL cup that 21 CFR 101.9 sets for nutrition facts panels, and the metric cup is the 250 mL cup in Australian, Canadian and UK metric recipes. The small gap between 236.588 mL and 240 mL (about 1.4 percent) is why a gallon holds only 15.77 nutrition label cups.

Is a dry gallon different from a liquid gallon?

Yes. NIST lists the dry quart at 1.101221 L and the peck at 8.809768 L. A dry gallon is four dry quarts, or half a peck, so it holds 4.405 L, which is 18.62 US cups. A dry quart is about 16 percent larger than a liquid quart (1.101221 L against 0.9463529 L). This page uses the liquid gallon throughout unless it says otherwise.

Frequently asked questions

How many cups are in a half gallon of milk? Eight US cups, which is 64 fl oz or 4 pints.

How many bottles of water are in a gallon? About 7.57 bottles of 500 mL (16.9 fl oz), so you need 8 bottles to cover a gallon.

How many cups are in a liter? About 4.23 US cups (1,000 / 236.588). For milliliter amounts, use our mL to cups converter.

How many ounces are in a cup? Eight fluid ounces in a US customary cup. Our ounces in a cup page covers fluid ounces against weight ounces.

How many cups are in a quart? Four US cups, which is 32 fl oz or 2 pints.

Conclusion

A US gallon holds 16 cups, and every smaller unit divides evenly from there. Recipes go wrong when US and Imperial measures mix, so check which gallon yours means. For recipes to measure out, see the TheSawad cookbooks.