Volume and weight are not the same thing
A cup measures volume — the space something takes up — while a gram measures weight. Two ingredients can fill the same cup and weigh completely differently: a cup of flour is around 120g, while a cup of honey is around 340g, because honey is denser. That's why converting between volume and weight units needs to know which ingredient you're measuring, while converting cups to milliliters or grams to ounces does not.
Where the density values come from
The grams-per-cup figures used here are typical values from general baking references for common ingredients like flour, sugar, butter and rice. They're a solid estimate for everyday cooking and baking, but real densities vary a little depending on how an ingredient is packed, sifted or scooped — spooning flour into a cup versus scooping it directly from the bag can differ by 10-15%.
When to weigh instead of measure by volume
For precise baking — bread, pastry, anything where ratios matter a lot — weighing ingredients on a kitchen scale is more accurate than scooping cups, because volume measurements are sensitive to how tightly an ingredient is packed. This converter is most useful for adapting a recipe written in one unit system to whatever tools you have on hand, or for a quick sanity check.
Frequently asked questions
Why does the ingredient I pick change the result?
Only when converting between a volume unit (like cups) and a weight unit (like grams). A cup of flour weighs a lot less than a cup of honey, so the calculator needs to know which ingredient to use its density. Converting cups to milliliters, or grams to ounces, doesn't need an ingredient at all.
How accurate are these conversions?
Volume-to-volume and weight-to-weight conversions are exact. Volume-to-weight conversions use typical densities from general baking references, which can vary somewhat depending on how an ingredient is packed or sifted, so for critical baking, weighing on a kitchen scale is always more precise.
How many millilitres are in a cup?
A US cup is about 237 mL; a metric cup is 250 mL.
How many teaspoons are in a tablespoon?
Three. One tablespoon is about 15 mL and one teaspoon about 5 mL.
Are grams and millilitres the same in cooking?
Only for water. Ingredients have different densities — a cup of flour weighs far less than a cup of sugar — so weight and volume are not interchangeable.