A cup is a measure of volume, but grams measure weight — and different ingredients weigh very different amounts for the same cup. A cup of flour is about 120 g, but a cup of honey is nearly three times heavier at 340 g.
For baking, weighing in grams is far more accurate than scooping cups, which is why professional recipes use it. Select your ingredient and this converter uses its real density to give you the exact gram weight.
Frequently asked questions
Why isn't one cup always the same in grams?
Because a cup measures volume. A cup of a light ingredient (flour, oats) weighs far less than a cup of a dense one (honey, butter), so grams differ per ingredient.
How many grams is a cup of flour?
About 120 g for all-purpose/plain flour, spooned and levelled. Packing it down can push it to 150 g or more, which is why weighing is more reliable.
Are US and UK cups the same?
A US cup is 236 ml and a UK/metric cup is 250 ml — close but not identical. This tool uses US-cup densities, the most common in recipes.