Grams to cups converter

How the conversion works

A US cup is a fixed volume: 236.5882365 millilitres, by the definition in NIST Handbook 44. What changes from one ingredient to the next is how much that volume weighs. So every by-ingredient conversion is two steps:

grams = cups x grams per cup for that ingredient

cups = grams / grams per cup for that ingredient

For 100 g of all-purpose flour at 120 g a cup, that is 100 / 120 = 0.833 cups. The converter also writes the result in measuring cups and spoons, rounded to the nearest 1/8 teaspoon: 3/4 cup + 1 tbsp + 1 tsp. That is the amount you would scoop if you had no scale.

Where the weights come from

Each ingredient has two published sources where both exist:

• USDA FoodData Central, the US Department of Agriculture's food database. Its SR Legacy release lists household measures, such as "1 cup = 125 g" for all-purpose flour.
• King Arthur Baking's ingredient weight chart, written by a US flour company for home bakers. It states how the cup is filled: flour is fluffed, spooned in and levelled.

The two often disagree, and the gap is real information. USDA puts a cup of bread flour at 137 g; King Arthur says 120 g. Neither is wrong. They describe differently filled cups. The full table below shows both figures for every ingredient and marks the one the converter uses in bold.

The rule for choosing: for flours, starches, sugars, cocoa, oats and chocolate chips the converter uses King Arthur's figure, because the cup-filling method is stated and matches how most US recipe writers measure. For liquids, oils, syrups, dairy, nuts, salt and leaveners it uses USDA's figure. King Arthur rounds many of those to whole ounces, which is why water, milk, cream and yogurt all appear in its chart at 227 g, exactly 8 oz. Butter is the one exception, explained on the butter converter page.

Why your cup may weigh more

The biggest source of error is how the cup gets filled. King Arthur's measuring guide says a cup of all-purpose flour holds 120 g when the flour is fluffed and spooned in, and up to 160 g when it is packed down. Scooping straight from the bag lands somewhere between. If a recipe was written by someone who scoops, its "cup" of flour is heavier than ours, and a weight conversion of their recipe will come out light. The guide to measuring flour covers this in detail.

Two other things move the numbers:

• Sifting makes a cup lighter. USDA lists powdered sugar at 120 g a cup unsifted and 100 g sifted.
• Packing makes it heavier. Brown sugar in a US recipe means packed: USDA gives 220 g packed against 145 g loose.

Cups are not the same size everywhere

The converter's "cup" is the US customary cup unless you choose otherwise. A metric cup, used in Australia, Canada and New Zealand, is 250 mL, about 6% larger. If your recipe is Australian, pick "Metric cups" in the From or To box; the weight per cup scales with it. The cups to ml converter compares all four cup sizes.

Every ingredient in the converter

Grams for the common cup fractions, with the published figure each one comes from. KA is King Arthur Baking; USDA is FoodData Central (the link opens the food's record).

When to trust a cup conversion, and when to weigh

A cup-to-gram conversion is good enough for most cooking: soups, sauces, rice, oats, oil, milk. For bread, cakes and pastry, where 15 g of flour changes the texture, weigh if you can. NIST's kitchen measurement tips say the same: measuring by mass with a kitchen scale is more accurate than measuring by volume. When the converter's figure and the recipe's own gram figure disagree, use the recipe's. The author weighed their cup; we can only report a typical one.