How Many Grams in a Cup of Flour? Why the Answer Depends on the Ingredient

Search for “how many grams in a cup” and you’ll find a dozen confident answers that disagree with each other. They’re not all wrong. The problem is the question: a cup measures volume, and grams measure weight. How much a cup weighs depends entirely on what’s in it.

A cup of water weighs about 237 grams. A cup of flour weighs roughly half that. A cup of honey weighs nearly half as much again as the water. If a converter gives you one number for “a cup in grams” without asking what you’re measuring, it’s guessing.

Volume versus weight

Every ingredient has a density: how much a given volume of it weighs. Water is the reference point at about 1 gram per millilitre. Flour is light and full of air. Honey and syrups are heavy. Butter sits a little under water.

So converting cups to grams is really two steps: turn cups into millilitres (one US cup is about 237 mL), then multiply by the ingredient’s density. That second step is the one most converters skip.

Common conversions for one US cup

These are typical values. Different sources vary by a few grams, and the next section explains why.

Ingredient	One US cup
Water	about 237 g
All-purpose flour	120 to 125 g
Granulated sugar	about 200 g
Brown sugar, packed	about 215 g
Butter	about 227 g (two US sticks)
Honey	about 336 g
Milk	about 244 g

Why recipes disagree about flour

Flour is the ingredient everyone argues about, because how you fill the cup changes how much flour is in it. Dip the cup into the bag and pack it down, and you can get 150 grams or more. Spoon the flour in loosely and level it with a knife, and you get closer to 120. That 25 percent difference is the gap between a tender cake and a dry one.

This is why professional bakers, and most recipes written outside North America, measure by weight. A gram of flour is a gram of flour however you scoop it.

If a recipe gives both cups and grams, trust the grams. The author weighed their ingredients; the cup measure is the translation.

Converting a recipe the easy way

You can do this by hand with a table like the one above, but it gets tedious across a whole ingredient list, and it’s easy to make a mistake halfway through.

KitchenCalc does it with each ingredient’s own density. Its built-in database covers 95+ ingredients, so 1 cup of flour comes out at 125 g and 1 cup of honey at 336 g, not the same number for both. It works in both directions (every volume unit to every weight unit and back), takes fractions the way recipes write them, so you can enter 2¼ cups instead of 2.25, and lets you add your own ingredients with a custom density if something isn’t on the list.

It runs entirely on your Mac with no account and no subscription.

A few habits that help

• Buy a kitchen scale. A basic digital scale costs less than a bag of good chocolate and removes the guesswork for good.
• Use the tare button. Put the bowl on the scale, zero it, add the first ingredient, zero it again, add the next. One bowl, no measuring cups to wash.
• Weigh sticky things. Honey, syrup and peanut butter cling to measuring cups. Weighing them straight into the bowl is both more accurate and less mess.
• Keep liquids by volume if you like. For water and milk the difference between volume and weight is small, so a measuring jug is fine.