Two people bake the same cookie recipe from the same page and get different results. Nobody made a mistake — they just filled the measuring cup differently. Volume measuring is the quiet reason home baking is inconsistent, and weighing is the fix. Here’s why, and how to switch.
Short answer: A “cup” of flour varies by 20–30 grams depending on how you scoop, which is enough to change the result. Bake by weight instead: use the per-ingredient grams in the table below (a cup of all-purpose flour is ~120 g), and the Unit Converter for the unit math around them — grams to ounces, millilitres to cups.
The problem with the cup
A cup is a measure of volume — space — but baking is chemistry, which cares about mass. The trouble is that dry ingredients pack differently every time:
- Scoop straight from the bag and you compress the flour: a cup can reach 150 g or more.
- Spoon it in and level off and it’s airy: closer to 120–125 g.
That’s a 20–30% swing in the single most important ingredient, from nothing but technique. Flour is the worst offender, but brown sugar (packed vs. loose) and powders behave the same way. Volume can’t see the difference; a scale can.
Why grams win
Weight is unambiguous: 120 grams is 120 grams regardless of who’s holding the cup, how humid the kitchen is, or how settled the bag got in shipping. It’s also faster and cleaner — set the bowl on a scale, press tare (zero), and pour until the number is right. No nested cups to wash, no leveling with a knife. This is why nearly every professional and European recipe lists grams first.
Common ingredients by weight
These are the standard conversions recipes assume. Note how different they are — this is exactly why you can’t use one blanket factor:
| Ingredient (1 US cup) | Approx. weight |
|---|---|
| All-purpose flour | 120 g |
| Granulated sugar | 200 g |
| Brown sugar (packed) | 220 g |
| Butter | 227 g |
| Water | 237 g |
| Honey | 340 g |
A cup of honey weighs nearly three times a cup of flour. “One cup” tells you almost nothing about mass until you know what’s in the cup — so take the gram weight per ingredient from the table, not one blanket number. From there the Unit Converter handles the unit math around it — grams to ounces if your scale reads imperial, or millilitres to cups for liquids.
Scaling a recipe without wrecking it
Once a recipe is in grams, resizing it is just multiplication — and far more reliable than juggling “two-thirds of three-quarters of a cup.” To double it, double every gram figure. To make 1.5× or 60% of a batch, the Percentage Calculator keeps the ratios exact so the balance of flour to sugar to fat stays true. That proportion is what makes a recipe work; weight is what lets you preserve it at any size.
Getting started
You don’t need to relearn cooking — just baking, where precision matters most. Buy a cheap digital kitchen scale, and when a recipe gives cups, convert the key dry ingredients to grams once and write them in the margin. After a few bakes you’ll trust the scale and never go back to guessing whether that was a packed cup or a loose one. For the broader metric-versus-imperial conversions around the kitchen and beyond, see the metric ↔ imperial cheat sheet.