How Many Grams In 1 Cup Flour? | The Exact Number Changes Your Bake

One cup of all-purpose flour equals 120 to 125 grams depending on the measuring method and brand, with King Arthur Baking standardizing on 120g per cup.

Every baker hits this moment: a recipe calls for cups of flour, but the scale sits right there. Scooping one way gives you 120g. Scooping another gives you 150g. That 30-gram difference is the line between a tender biscuit and a hockey puck. The real number depends on two things — how you measure and whose flour you use. Here is the breakdown that gets your bake right every time.

Why One Cup of Flour Weighs Different Amounts

Flour settles, compresses, and aerates differently depending on how it hits the cup. The weight you get is not a property of the flour itself — it is a property of your measuring technique.

The US standard cup holds 240ml. But flour weighs less than water because it is full of air. How much air you trap in that 240ml space is what changes the gram count. The official US cup volume is fixed. The grams that fill it are not.

Grams Per Cup By Flour Type And Brand

Different brands mill flour differently. A King Arthur cup of all-purpose flour weighs less than a Gold Medal cup. Here is how the major US brands and flour types stack up.

The Measuring Method That Gives You 120g

The standard that most US recipe book authors assume is the “Scoop and Level” method. This is the technique that produces the 120–125g result. It is also the method that King Arthur Baking uses for their ingredient weight chart.

Step 1 — Fluff the flour. Run a spoon or whisk through the flour in your bag or container. This breaks up any settling that happened during shipping and storage. Flour that sat in a pantry for three weeks is denser at the bottom than at the top — fluffing resets that.

Step 2 — Spoon into the cup. Use that same spoon to gently transfer flour into a dry measuring cup. Let it heap above the rim. Never dunk the cup straight into the bag — that is the “Dip and Sweep” method that packs in 140 to 150g.

Step 3 — Level with a straight edge. Take a knife, spatula, or bench scraper and sweep it across the rim of the cup. The excess flour falls away. The cup now holds one level cup of aerated flour.

The cue you succeeded: the flour sits level with the rim, no packed gaps at the bottom, and the cup feels lighter than you expected. Weigh it on a scale. It should land between 120g and 125g.

What Changes The Weight — The Three Gotchas

Even experienced bakers land on different weights for the same recipe. These three factors are why.

Flour brand. Gold Medal all-purpose flour comes in at 130g per cup using the same spoon-and-level method. King Arthur hits 120g. If you switch brands, your baked good changes even if you measure the exact same way. The fix is simple: check the nutrition label on your specific bag. Most US flour brands list a serving size in grams (like “1/4 cup = 30g”). Multiply by four. That is your baseline for that bag.

Measuring method. Dip-and-sweep produces 140–150g per cup because the flour compresses as the cup pushes into the bag. That is a 25% increase from the spoon-and-level method. A recipe written for one method will fail with the other. Stick to the method the recipe author used — most modern US baking sources use spoon-and-level unless they say otherwise.

Hydration and humidity. Flour absorbs moisture from the air. On a humid summer day, the same cup of flour can weigh 5 to 8 grams more than on a dry winter afternoon. This is why pastry chefs weigh flour instead of measuring it — weight is stable even when the air is not.

The only gate for this topic is your kitchen. Every US home baker can access these methods. The one exception: if you are following an Australian, Canadian, or South African recipe, their cup equals 250ml, not 240ml. That extra 10ml translates to roughly 130g of all-purpose flour per cup. Do not use US gram conversions on non-US recipes.

Why Those 10–15 Grams Matter So Much In Baking

Baking is a chemical reaction. Flour provides structure through gluten formation and absorbs liquid. Too much flour and the dough is dry, the crumb is tight, and the bake is dense. Too little and the structure collapses, the texture is gummy, or the bake spreads instead of rises.

A 10–15 gram variance in a single cup of flour — which is roughly a 10% swing — is enough to change the outcome of cookies, cakes, and breads. America’s Test Kitchen has shown that this small difference determines whether a chocolate chip cookie spreads into a thin disc or stays thick and chewy. That is the difference between a 120g cup and a 135g cup.

The One Tool That Eliminates The Guesswork

A digital kitchen scale removes every variable. It does not care how you scoop, what brand of flour you bought, or how humid your kitchen is. It gives you the same number every time. Most serious bakers and recipe developers use scales because cup measurements introduce inconsistency that week-to-week bakers feel as “this recipe worked last time but not today.”

The King Arthur Baking ingredient weight chart, published in August 2024, lists 120g for all-purpose flour. Gold Medal’s specifications differ. The USDA lists 125g. None of these are wrong — they all reflect a valid measurement of one cup of flour. The problem is that they are not interchangeable in a recipe that expects one specific weight.

When you need precision without a scale, follow the spoon-and-level method on the exact brand bagged for your recipe, and read the label for that brand’s serving weight. That label is the only source that knows how that specific flour settles and packs.