How many cups in a gallon (and other kitchen measures)
Updated on July 3, 2026 · by Rafael Rossi
Sixteen. A US gallon holds 16 cups. But the useful version of that answer is the whole chain of doublings behind it — and the two traps that quietly ruin recipes: the gallon that is not always the same gallon, and the fact that a cup of flour has no fixed weight.
The chain that makes it memorable
The entire US volume system is built on doubling:
| Measure | Equals | In millilitres |
|---|---|---|
| 1 teaspoon | — | ~5 ml |
| 1 tablespoon | 3 tsp | ~15 ml |
| 1 fluid ounce | 2 tbsp | ~30 ml |
| 1 cup | 8 fl oz | ~237 ml |
| 1 pint | 2 cups | ~473 ml |
| 1 quart | 2 pints / 4 cups | ~946 ml |
| 1 gallon | 4 quarts / 16 cups | ~3,785 ml |
Two cups make a pint, two pints make a quart, four quarts make a gallon. Remembering that chain removes the need to memorise any millilitre figure.
Trap 1: the US gallon is not the Imperial gallon
This is the difference that most often ruins a recipe — and it is large.
The British Imperial gallon holds 4,546 ml against the US gallon's 3,785 ml. It is 20% larger. And the difference propagates down the whole chain: an Imperial pint is 568 ml, a US pint 473 ml.
So an older British recipe asking for "1 pint of milk" is asking for nearly 100 ml more than the same phrase in an American one. In a cake batter, that is the difference between batter and soup.
The fluid ounce diverges too: 29.57 ml in the US system against 28.41 ml Imperial. Which produces a genuinely confusing result — an Imperial pint is 20 fl oz while a US pint is 16.
Trap 2: dry cups and liquid cups are not interchangeable
They hold the same volume, but they are built for different jobs, and swapping them introduces error.
A liquid measuring cup is a jug with graduations below the rim, read at eye level — you cannot fill it to the brim without spilling. A dry measuring cup is filled to the top and levelled off with a straight edge, which is the only way to measure a powder accurately.
Measuring flour in a liquid cup means eyeballing a line through a curved wall against a heaped, uneven surface. Measuring water in a dry cup means filling to the brim and carrying it. Both work badly.
Trap 3: a cup is volume, not weight
Here is the error that frustrates bakers most. A cup of flour has no fixed weight — it depends on how the flour got into the cup.
Flour scooped straight from the bag can weigh up to 20% more than flour spooned in and levelled. In a cake, that difference changes the texture completely, and it is the most common explanation for "I followed the recipe and it did not work".
| Ingredient | 1 cup weighs about |
|---|---|
| All-purpose flour | 120 to 125 g |
| Granulated sugar | 200 g |
| Brown sugar, packed | 220 g |
| Butter | 227 g (2 sticks) |
| Water or milk | ~240 g |
| Cocoa powder | 85 g |
| Uncooked rice | 185 g |
The same cup holds 85 g of cocoa and 227 g of butter. There is no single cup-to-gram conversion — it changes with the ingredient's density.
The fix: weigh the dry ingredients
Professional baking measures by weight precisely because volume is imprecise for powders. An inexpensive digital scale solves it permanently and produces less washing up.
Without a scale, use the spoon-and-level method: fluff the flour with a fork, spoon it into the cup without packing, and level with the back of a knife. Never scoop the cup through the bag — that is the motion that compacts and adds the 20%.
Frequently asked questions
How many cups in a half gallon? Eight. A half gallon is 2 quarts, and each quart is 4 cups — the standard milk carton.
Is a tablespoon always 15 ml? In recipes, yes by convention. The spoon in your drawer may hold anywhere from 10 to 20 ml, which is why measuring spoons exist. With baking powder or salt, the difference matters.
Is a fluid ounce the same as an ounce? No, and it is a frequent trap. A fluid ounce measures volume (~30 ml); an ounce measures mass (28.35 g). They coincide only by accident, and only for water.
What is a stick of butter? A US-standard block: 1 stick = 1/2 cup = 8 tablespoons = 113 g. The wrapper is printed with tablespoon marks, which makes it the easiest ingredient in American baking to measure accurately.