Step by step
- Write the recipe out one line per ingredient, with the amount, the unit and exactly what the ingredient is: "packed brown sugar", not "sugar".
- Match each ingredient to a weight. The grams to cups converter has 44 ingredients with published weights. Flour type matters: bread, cake and all-purpose flour differ in some sources.
- Convert the amount, including fractions. 2 1/4 cups of flour at 120 g a cup is 270 g.
- Round sensibly. Whole grams for anything over 10 g. For leaveners and salt, keep one decimal if your scale reads to 0.1 g; otherwise keep the teaspoon measure for those lines.
- Keep counted items as counts. Eggs, whole bananas and similar items vary in size; a recipe that says "2 large eggs" is fine as written.
- Bake once and compare. If the result is drier or wetter than you are used to, the original author probably filled their cups differently. Adjust the flour line first.
A worked example
A typical US chocolate chip cookie recipe, converted with the figures this site uses:
| Recipe line | Weight per cup used | Grams |
|---|---|---|
| 2 1/4 cups all-purpose flour | 120 g (King Arthur) | 270 |
| 1 tsp baking soda | 220.8 g, from 4.6 g a tsp (USDA) | 4.6 |
| 1 tsp table salt | 292 g (USDA) | 6.1 |
| 1 cup butter (2 sticks) | 226 g (King Arthur) | 226 |
| 3/4 cup granulated sugar | 198 g (King Arthur) | 148.5 |
| 3/4 cup packed brown sugar | 213 g (King Arthur) | 159.8 |
| 2 large eggs | counted | 2 eggs |
| 2 cups chocolate chips | 170 g (King Arthur) | 340 |
Rounded for a scale that reads whole grams: 270 g flour, 226 g butter, 149 g granulated sugar, 160 g brown sugar and 340 g chocolate chips, with the baking soda and salt left as 1 teaspoon each unless your scale reads to 0.1 g.
Lines that need care
- Brown sugar in US recipes is packed unless it says otherwise. USDA lists a loose cup at 145 g and a packed cup at 220 g.
- Powdered sugar is unsifted unless the recipe says "sifted". Sifted, USDA gives 100 g a cup against 120 g unsifted.
- Salt depends on the type. A tablespoon is 18 g of table salt, 8 g of Diamond Crystal kosher and 16 g of Morton kosher in King Arthur's chart.
- Liquids are often fine left in cups or millilitres, since a liquid fills a cup the same way every time. Weighing them is still quicker if the bowl is already on the scale.
- "1 cup flour, sifted" and "1 cup sifted flour" are different. The first means measure, then sift; the second means sift, then measure, which gives less flour.
Why bother
Two reasons. A weight is the same whoever measures it, so the recipe comes out the same each time. And it is faster: one bowl on a scale, reset to zero between ingredients, with no cups to wash. NIST's metric kitchen recommends weighing with a kitchen scale over volume measures for accuracy.