US cups to grams: flour, sugar, butter and more

What a cup is

A cup measures volume, and a gram measures mass, so there is no single conversion. The same cup holds very different weights of flour and honey. A US cup is 236.588 ml. A metric cup is 250 ml, and the old UK imperial cup was about 284 ml. Nutrition labels in the US use a 240 ml cup. Recipes from other countries may mean any of these, so check the source before converting. The last column in the table below gives grams for a 250 ml metric cup.

Grams per cup: the 10 dry ingredients bakers use most

These are typical values for ingredients that were spooned into the cup and levelled. Brands, humidity and technique shift them by 5 to 10 percent. Pick one source and stick with it, since a recipe written with 120 g flour per cup will not behave the same if you assume 140 g.

Fats and liquids for comparison

A stick of US butter is 1/2 cup, 8 tablespoons or 113 g. For more liquids, see the liquid measuring units guide and the liquid volume to weight converter.

Common fractions of a cup

Use this for recipes that call for a part of a cup. To convert any gram figure to ounces, multiply by 0.03527 (divide by 28.35).

The compaction trap: why flour is the troublemaker

Powders contain a lot of empty space between their tiny, irregular particles, so they compress under their own weight. Sugar and salt are rigid crystals that keep their gaps, but flour settles. In a bag on the shelf, the top layers press the air out of the bottom layers and the particles interlock. Plunge a cup into that bag and you cram tightly packed flour into the cup: it can weigh 140 to 150 g. Whisk the same flour to aerate it, spoon it gently into the cup and level it, and the cup weighs about 110 to 120 g.

That 30 g gap is about a quarter of a cup's worth of flour. In a delicate cake it upsets the ratio of dry powder to fat, eggs and liquid, leaving a batter that is too dry, with too little steam to expand, so the cake turns out tough, crumbly or rubbery instead of tender. This is the main reason most bakers prefer a scale.

Sugar is steadier. Granulated sugar flows into the cup and settles at about 200 g either way. Brown sugar is meant to be packed, which is why its cup is heavier. Powdered sugar is fluffy and packs easily, so spoon and level it, or sift first if the recipe says "sifted".

Baking powder: weigh it when you can

Baking powder is an ultra-fine powder that compacts easily and clumps, so a teaspoon can vary a lot from one scoop to the next. A level teaspoon is typically about 4 to 5 g. For large batches or very delicate bakes, weigh it on a scale that reads to 0.1 g. On the tin, look for:

• Double-acting. It releases gas twice, first when it meets wet ingredients and again in the oven's heat, which gives cakes an even, airy crumb and helps breads rise consistently.
• Aluminum-free. Standard baking powders can leave a tinny, metallic aftertaste in delicately flavoured bakes such as sponge cakes or sugar cookies.
• A fresh date. Moisture in the air destroys it. If a tin has been open for more than about six months, it may have lost strength, and cakes can sink or breads turn out dense. A spoonful in hot water should fizz right away.

How to measure dry ingredients by volume

1. Fluff the ingredient. Stir flour, cocoa and powdered sugar in their container to loosen them.
2. Spoon, don't scoop. Use a spoon to pile the ingredient into a dry measuring cup until it overflows. Do not tap or shake the cup.
3. Level it. Sweep the back of a knife across the rim so the surface is flat.
4. Pack only when told to. Press brown sugar firmly into the cup, then turn it out and it should hold the shape of the cup.
5. Use the right cup. Dry ingredients go in nesting cups you can level. Liquids go in a clear jug with a pouring spout.
6. Use real measuring spoons for small amounts. A teaspoon from the cutlery drawer is not 5 ml.

How to measure by weight

A kitchen scale is the most reliable tool you can buy for baking. Set the bowl on the scale, press tare to zero it, then add the first ingredient until the display shows the right number of grams. Press tare again and add the next. You use fewer dishes, and the result is the same every time.

• Set the scale to grams. Many also read in ounces, so check the unit.
• Tap tare between ingredients so each number is the amount added.
• Pour slowly near the target. It is easier to add than to remove.
• Weigh small amounts such as yeast or baking powder on a scale that reads to 0.1 g, or measure them by the spoon.

Converting a recipe from cups to grams

1. Write down each ingredient and the cups or spoons it needs.
2. Find each ingredient in the tables above and multiply: grams per cup times the number of cups.
3. Round to the nearest gram for dry ingredients and for butter.
4. Write the gram values in the margin of the recipe, so you only convert once.

Example: a cookie recipe needs 2-1/4 cups flour, 3/4 cup granulated sugar, 3/4 cup packed brown sugar and 1 cup (2 sticks) butter. That is 2.25 × 120 = 270 g flour, 0.75 × 200 = 150 g sugar, 0.75 × 213 = 160 g brown sugar and 227 g butter.

Choosing flour: protein content

The key figure on a flour bag is the protein content, because protein decides how much structure the baked good has.

On the label, "bleached" flour has been treated with chemical agents to speed up ageing, which weakens the proteins and suits tender cakes. "Unbleached" flour ages naturally and keeps its protein strength, which suits structural baking such as bread. Many bread flours also contain malted barley flour, an enzyme-rich ingredient that breaks starch down into sugars, feeding the yeast for a better rise and a darker crust.

The science: gluten and starch

When water meets flour, two reactions happen at once. Wheat flour holds two main proteins: gliadin, which gives elasticity and stretch, and glutenin, which gives strength. In dry flour they are coiled up and dormant. As soon as liquid arrives they hydrate, uncoil and link into a sticky, rubbery network called gluten. Kneading stretches and aligns the chains into a web. When yeast releases carbon dioxide, the web traps the gas in countless tiny bubbles, like a mass of small balloons, and the bread rises.

Gluten builds the walls and starch fills them in. Flour is mostly starch granules. As a batter or dough bakes and passes about 140°F (60°C), the granules absorb the surrounding water and swell, then burst and release a cloudy gel that sets into a firm structure. This is gelatinisation. Together with gluten it sets the crumb of a cake or loaf so that it does not collapse as it cools.

Salt and other ingredients that differ by type

Salt is the one dry ingredient where the type matters as much as the cup. Fine table salt weighs about 288 g per cup, but coarse kosher salts are lighter because the crystals are larger or hollow, and Diamond Crystal and Morton differ by almost a factor of two. When a recipe gives salt in grams, follow it. If it gives teaspoons, check which brand the author used.

Chocolate chips, nuts and dried fruit vary by size and brand, so a cup of one product can differ from another by 10 percent. For these, weigh when you can.

Common mistakes

• Scooping flour straight from the bag.
• Using a liquid measuring jug for dry ingredients.
• Assuming a cup of one ingredient weighs the same as a cup of another.
• Mixing US, metric and UK cups in one recipe.
• Forgetting that a recipe in grams may assume a particular flour: bread flour absorbs more water than cake flour.

Need a different unit? Try the fluid converter, ounces to grams or how to scale a recipe.

Related converters