Cups to grams converter

How is it calculated?

The conversion runs in two steps. First the measure's volume is taken in millilitres — a 200 ml glass, a 100 ml small glass, a 15 ml tablespoon, a 10 ml dessert spoon, a 5 ml teaspoon, a 300 ml bowl, a 330 ml can. Then that volume is multiplied by the food's bulk density to give grams, and the calories and macros follow from the grams.

Bulk density is not the density of the substance: what goes into the cup is the food plus the air between the pieces. A walnut is denser than water, yet shelled walnuts in a cup come to 0.42 g/ml because half of that volume is the air trapped between the pieces, which is why these numbers answer the question actually being asked — how much fits in the cup.

The densities were not weighed in our kitchen and invented. They are derived from the standard portion weights USDA FoodData Central publishes for each food, so they can be checked: 240 millilitres of cooked rice comes to 158.4 grams here, matching USDA's "1 cup = 158 g".

Cup sizes differ by country, so every measure carries its volume in its name. A Turkish water glass is 200 ml, a US cup is 240 ml; both are separate options and neither stands in for the other. If you know the volume of the container in your hand, you know which row to read.

Where a food cannot be measured by volume, no measure is invented. Salmon, chicken thigh and anchovy list only grams and a typical serving; a fillet does not go into a cup and there is no such thing as "one slice of anchovy". 68 of the 80 foods can be measured by volume; the rest by count or by weight.

"A handful" is a convention, not a measurement. Because nothing was actually weighed, the gram figure it stands for is printed on screen; if your handful is fuller than that, switch to the gram field.

How to read your result

The first thing the tool shows is grams, not calories. The reason is simple: the calories of a food are written everywhere, while what is genuinely unknown is how many grams sit in the container in your hand, and the moment you have that number every other table — the back of the packet, the app's database — becomes usable. Grams come first.

Dry cereals are where the numbers surprise people most. A 200 ml glass of rolled oats is 68 grams, not 200; a glass of corn flakes is only 24 grams and 86 calories. "I had a cup of cereal" is a much smaller meal than most people assume.

The surprise runs the other way too: a 200 ml glass of honey is 282 grams and 857 calories. Given that the same glass holds 6.6 grams of popcorn, "a cup" on its own tells you nothing — the range spans forty-three fold.

Spoon measures are the biggest single source of everyday error. A tablespoon of olive oil is 13.5 grams and 119 calories; the same spoon of ketchup is 16.9 grams but only 17 calories. Adding "a spoonful" to a dish can mean a hundred-calorie difference depending on which spoonful it is.

These are averages. Heaping versus levelling, how finely something is chopped and how hard it is pressed into the cup move them within a 10-20% band, which is accurate enough to measure out a recipe but nowhere near accurate enough to argue over a single gram. If you need an exact number, weigh it. The package's own label is the next best thing.