Cups to Grams - Conversion by Ingredient

Why does the weight per cup vary?

A cup is a volume measurement: 236.59 ml. But grams measure weight. The link between volume and weight is density. Water is dense: 1 ml weighs roughly 1 gram, so a cup of water weighs about 237 grams. Flour is much less dense. Air fills the spaces between the grains. One cup of flour weighs only about 125 grams - barely half the weight of the same cup filled with water.

Honey sits at the other end. It is thicker and heavier than water. One cup of honey weighs 340 grams - nearly three times as much as the same cup of flour. This is why you cannot simply convert cups to milliliters and call it done. For baking, you need the gram weight for each specific ingredient.

When to use a scale vs. measuring cups

For liquids (water, milk, oil), cups work fine. Liquids have consistent density, so the volume-to-weight relationship is reliable. Pour to the line, read at eye level, done. A cup of milk is always about 245 grams.

For dry ingredients, a scale is better. Flour is the biggest offender: depending on how you scoop it, one cup can weigh anywhere from 120 to 160 grams. Sugar is more forgiving because the granules pack consistently. Butter is easiest - most US butter sticks have tablespoon markings printed on the wrapper.

Professional pastry chefs and serious home bakers weigh everything. A digital kitchen scale with 1-gram precision costs very little and pays for itself in consistent results. If a recipe provides both cups and grams, always go with grams.

The spoon-and-level method

If you must use cups for flour, use the spoon-and-level method. Stir the flour in its container to loosen it. Spoon flour into the measuring cup until it overflows slightly. Sweep the excess off with the flat side of a knife. Do not tap the cup or shake it - that compacts the flour and adds weight.

This method gives you about 125 grams per cup for all-purpose flour. The scooping method (dipping the cup directly into the flour bag) packs the flour and yields 140-155 grams. King Arthur Flour, one of the largest US flour brands, uses 120 grams per cup as their standard. Other sources say 125 or 128 grams. The variation proves why cups are imprecise for flour.

Brown sugar: packed or loose?

Brown sugar is special. Recipes say "1 cup packed brown sugar." That means you press the sugar firmly into the cup until it holds its shape when turned out. Packed brown sugar weighs about 220 grams per cup. Loosely scooped, it weighs only 145-165 grams. The difference is huge.

If a recipe just says "1 cup brown sugar" without the word "packed," assume packed. That is the default in American baking. If it says "lightly packed," aim for about 195-200 grams. When in doubt, use the scale.

Liquid ingredients: oil, honey and milk

Milk and water weigh about 245 grams per cup (slightly more than the 237 grams you might expect because milk is denser than pure water). Oil weighs about 218 grams per cup - lighter than water because oil floats. Honey and maple syrup are heavy: about 340 grams per cup.

For honey, grease the measuring cup first with a thin layer of oil or cooking spray. The honey will slide out completely instead of sticking to the sides. This trick also works for peanut butter, molasses and other sticky ingredients.