How this is calculated
Every ingredient carries one number: its weight in grams for one US cup, measured the way a careful baker would measure it — spooned in and levelled, not scooped and packed, unless the entry says packed. Everything else falls out of that:
- Tablespoon = cup ÷ 16. Teaspoon = cup ÷ 48. So 120 g of flour a cup is 7.5 g a tablespoon and 2.5 g a teaspoon.
- Ounces here are weight ounces: 28.35 g. A cup of butter is 227 g, which is 8.0 oz, which is two American sticks.
- Millilitres are volume: a US cup is 236.588 ml. A row entered in ml is converted to cups first, then multiplied by the density.
- Rows entered by weight run the other way — grams divided by the density gives the volume, which is how you get from “500 g flour” back to “4¼ cups”.
The scale factor is applied after conversion, to every row equally, and weights are then rounded to the step your scale can actually read.
Why a single cups-to-grams number does not exist
A cup is a measure of space. A recipe needs a measure of mass. The bridge between them is density, and density varies by a factor of four across an ordinary baking cupboard: 85 g for a cup of cocoa powder, 340 g for a cup of honey. Even inside one category the spread is real — cake flour 114 g, plain flour 120 g, bread flour 127 g. Convert a whole list with one factor and the errors compound in different directions on every line.
Worked example. A standard chocolate chip cookie recipe: 2¼ cups plain flour, 1 tsp baking soda, 1 tsp table salt, 1 cup butter, ¾ cup granulated sugar, ¾ cup packed brown sugar, 2 large eggs, 2 cups chocolate chips.
Flour: 2.25 × 120 = 270 g. Baking soda: 288 ÷ 48 = 6 g. Table salt: 292 ÷ 48 = 6.1 g. Butter: 227 g, which is 8 oz or two sticks. Granulated sugar: 0.75 × 200 = 150 g. Packed brown sugar: 0.75 × 213 = 160 g. Eggs: two large, out of the shell, about 100 g. Chocolate chips: 2 × 170 = 340 g.
Total batter weight 1,259 g. Now scoop the flour out of the bag instead of spooning it, at roughly 145 g a cup, and the flour line alone becomes 326 g — 56 g more than the recipe wanted, or an extra half cup that nobody measured and nobody can see. That is the difference between a cookie that spreads and a cookie that does not.
What this does not account for
- Your flour and your weather. Flour picks up moisture. A humid August kitchen and a dry February one will not give the same weight per cup even with identical technique. The published figures are a good average, not a measurement of your bag.
- How hard you pack. Brown sugar at 213 g a cup assumes it is firmly packed. Loosely spooned it is closer to 145 g. If a recipe does not say, assume packed.
- How finely something is chopped. A cup of coarsely chopped walnuts and a cup of finely chopped walnuts differ by more than 10%. Weight is the honest unit; the cup figure is an approximation of a variable thing.
- Metric cups. Everything here uses the US cup at 236.6 ml. Australian recipes use a 250 ml cup, which is 6% larger.
- Sticks and blocks. An American stick of butter is 113 g; a British block is 250 g. Enter the weight rather than converting through cups where you can.
- Eggs. Sized by weight in the shell, which is not the weight you use. A large US egg is about 50 g out of the shell, a UK large about 58 g. If a bake depends on it, weigh the beaten egg.
- Volume of liquids at temperature. Warm water weighs marginally less than cold. It has never mattered in a kitchen and it does not matter here.
Common questions
How many grams is a cup of flour?
120 g, spooned into the cup and levelled off. Bread flour is 127 and cake flour is 114. Scooping the cup through the bag compacts it to 140–150 g, which is up to a quarter more flour than the recipe asked for, and it is the most common single reason a bake comes out dry and tough.
Why does one cup weigh different amounts?
Because a cup measures space, not substance. Honey is four times denser than cocoa powder. Any tool that gives you one conversion factor for a whole recipe is giving you a number that is wrong on most of the lines.
Which kosher salt does a recipe mean?
Ask the recipe, because the two brands are not interchangeable. Diamond Crystal is 142 g a cup and Morton is 240 g — a teaspoon of one is 3.0 g and of the other 5.0 g. American recipes that say “kosher salt” usually mean Diamond Crystal. If you have Morton, use about two thirds as much; if you have table salt, about half.
How many grams in a tablespoon?
Divide the cup weight by 16. Flour 7.5 g, granulated sugar 12.5 g, butter 14.2 g, honey 21.3 g, cocoa 5.3 g, oil 13.6 g. A teaspoon is a third of a tablespoon.
Do I need to weigh liquids?
Water and milk, no — measuring by volume is close enough and faster. Honey, golden syrup, treacle and molasses, absolutely yes: weigh them straight into the bowl. Half a sticky ingredient stays in the measuring cup, and that half is a real error, not a rounding one.
Can I convert the other way, grams to cups?
Yes — set a row's unit to grams and the cup column fills in. It is how you take a European recipe and cook it with American measuring cups, and it is the same density table read backwards.
Why do different charts disagree?
Because they measured differently. A chart that scoops gets 145 g for a cup of flour and a chart that spoons gets 120. Neither is lying; they are describing different actions. Pick one chart, use it for everything, and your results become repeatable — which is the actual goal.
Is it worth buying a scale?
A digital kitchen scale is the cheapest meaningful upgrade in a kitchen. It removes the largest source of error in baking, it means one bowl instead of a sink of measuring cups, and it makes every recipe you scale come out the same as the last time.