Why a Cup of Flour Is Not a Cup of Sugar: Baking by Weight
Published · 3 min read · By The Samsung Calculator editorial team
Volume measures a space, not an amount
A US cup is 236.6 mL of space. Fill it with all-purpose flour and you have about 125 g. Fill it with granulated sugar and you have 200 g. Honey gives 340 g. The cup has not changed; the density of the contents has.
This is why a converter that turns cups into grams without asking what you are measuring is guessing, and why professional recipes are written in grams. A kitchen scale removes the single largest source of inconsistency in home baking.
The flour problem specifically
A cup of flour can weigh anywhere from 120 g to 150 g depending on how it was filled. Scooping the cup straight into the bag compacts the flour and adds 20% or more; spooning it in loosely and levelling the top gives the lower figure. Sifting first gives less again.
Twenty percent more flour in a cake is not a rounding error — it is a different recipe. It is the most common reason a bake comes out dry, dense or tough when the instructions were followed exactly. Most modern recipe developers, including King Arthur Baking, standardise on 120–125 g per cup using the spoon-and-level method.
Cups are not standard between countries either
A US cup is 236.6 mL, a US legal cup (used on nutrition labels) is 240 mL, a metric cup is 250 mL and an imperial cup is 284 mL. The 6% gap between US and metric cups is enough to matter in bread and pastry, where hydration ratios are tight, and largely irrelevant in a stew.
Tablespoons diverge too: 15 mL in most of the world, 14.79 mL in the US and 20 mL in Australia. An Australian recipe calling for four tablespoons of butter means 25% more than an American one.
When volume is fine
For liquids, volume is perfectly good — water, milk and stock have consistent density and a measuring jug is faster than a scale. For anything where the ratio matters structurally — flour, sugar, butter, leavening in a bake — weigh it. For a soup, measure however you like.
Convert your recipe
The cooking converter holds published densities for fifteen common ingredients, so cups to grams gives the right answer for the thing you are actually measuring. The butter converter handles sticks, and the oven temperature converter handles gas marks.
Run your own numbers
Convert any recipe measurement between cups, spoons, grams, ounces and millilitres using the real density of each ingredient — because a cup of flour and a cup of honey are not the same weight.
About this article
Written and reviewed by The Samsung Calculator editorial team. Every calculator is written against a published formula, reviewed against at least one independent reference implementation, and dated when it changes. Last updated June 28, 2026. Spotted an error? Tell us.