Why conversions vary between charts

Look up a cup of flour on five reputable sites and you will find answers from 120 g to 145 g. None of them are lying. Each chart measured with a different technique, and technique changes how much ingredient fits in the same cup. Once you know the four causes, the disagreements stop being confusing.

1. Scooping versus spooning

Dip a measuring cup into a flour bag and the cup compacts the flour as it fills, catching up to 140 or 145 g. Spoon flour into the cup and level it, and you get near 120 g. A chart built by bakers who scoop will run 15 to 20 percent heavier on every powdery ingredient than one built by bakers who spoon. This single difference explains most of the flour disagreement online.

2. Packing

Brown sugar is the famous case: recipes assume you press it firmly into the cup, which takes it from about 200 g loose to about 220 g packed. Shredded cheese, coconut and chopped herbs have the same problem with no agreed convention at all, which is why their published values scatter the widest.

3. Sifting and settling

Sifting adds air. Sifted powdered sugar drops from about 120 g a cup to about 100 g, and sifted flour loses close to 10 g. In the other direction, a bag of flour that has been sitting settles and packs itself, so even a spooned cup from the bottom of an old bag weighs more than one from a freshly fluffed container.

4. Which cup

A US cup is 236.6 ml, a metric cup is 250 ml, and old British recipes may mean 284 ml. A chart written for metric cups reads about 6 percent heavier across the board than a US chart, before any technique differences begin. The full breakdown is on US cup vs metric cup.

What to do with disagreeing charts

Use a chart that names its method, and match it to what your recipe author does. This site states the method beside every figure: our flour is spooned and levelled at 120 g, our brown sugar firmly packed at 220 g, our powdered sugar unsifted at 120 g. The full list with sources is on the density data page.

And when the result truly matters, skip the argument entirely. A 15 dollar kitchen scale reads the same in every country, every humidity and every measuring style.