Every flour is a protein number and a cup weight. Get those two right and you can predict how any flour behaves before you open the bag.
Flour is graded by one number that matters more than any other: protein content. Protein is what becomes gluten when flour meets water, and gluten is the elastic network that traps gas, holds shape, and decides whether a crumb is chewy, tender, or crumbly. A 7% flour and a 14% flour are different ingredients wearing the same word.
The second number that matters is weight per cup, because flours vary from about 95 g to 167 g per US cup — a 75% spread. A recipe written for cake flour by volume will be badly over-floured if you scoop bread flour into the same cup. Every conversion on this site uses a fixed, published gram weight per flour so that never happens.
Protein ranges are typical published values for US retail flours; individual brands sit at specific points inside them (King Arthur all-purpose, for example, runs near 11.7%, Gold Medal closer to 10.5%). Cup weights are the spoon-and-level values used across CupOrGram.
| Flour | Protein | Grams per cup | Best for |
|---|---|---|---|
| Cake flour | 7–9% | 114 g | Sponge, chiffon, angel food, tender layer cakes |
| Pastry flour | 8–10% | ~115 g | Pie crust, biscuits, tart shells |
| Self-rising flour | 8–10% + leavener | 113 g | Biscuits, pancakes, quick breads |
| All-purpose (plain) flour | 10–12% | 125 g | Cookies, muffins, most everyday baking |
| Bread flour | 12–14% | 130 g | Yeast breads, pizza, bagels |
| Whole wheat flour | 13–14% | 120 g | Hearty loaves, rustic quick breads |
| Spelt flour | 12–13% (fragile gluten) | 120 g | Soft loaves, muffins, crackers |
| Rye flour | 8–11% (little gluten) | 102 g | Rye and sourdough loaves, crispbreads |
| Semolina (durum) | 12–15% | 167 g | Pasta, semolina bread, dusting |
| Almond flour | 21% (no gluten) | 96 g | Macarons, financiers, gluten-free cakes |
| Oat flour | 13% (no gluten) | 95 g | Pancakes, muffins, gluten-free quick breads |
| Gluten-free blend | varies (xanthan added) | 156 g | 1:1 swaps in cakes and cookies |
Cake flour (7–9%) is milled from soft wheat and usually chlorinated, which weakens its gluten further and helps starch absorb more liquid and sugar. That's why it makes the finest, most tender crumb — and why it collapses if you ask it to hold a yeast bread together.
All-purpose flour (10–12%) is a blend of hard and soft wheat, strong enough for a sandwich loaf and soft enough for a muffin. It is what most recipes mean when they just say "flour". The UK calls it plain flour and India calls it maida — same product, different passport.
Bread flour (12–14%) is hard red wheat. The extra protein builds a stronger, more elastic gluten network that holds gas through a long rise and gives the chew you want in a baguette or a bagel. In cookies it pushes the texture toward chewy-bready; in cake it's a mistake.
Whole wheat flour looks high in protein (13–14%) but bakes denser than bread flour, because the bran shards physically cut gluten strands as you knead. It also absorbs more water, so most whole-wheat recipes carry 5–10% more liquid and benefit from a rest before kneading.
Spelt has plenty of protein, but its gluten is more fragile and water-soluble than modern wheat's. Knead it less and handle it gently; over-mixed spelt doughs go slack and spread. Rye contributes almost no usable gluten — instead, gummy fibres called pentosans hold the structure, which is why rye doughs are sticky and rise low, and why most rye breads blend in wheat flour.
Semolina is coarsely ground durum, the hardest wheat, with a strong but brittle gluten and a yellow colour from carotenoids. It is the flour for pasta and the golden crust on a semolina loaf, and it is dense: 167 g per cup, the heaviest flour on the list.
Almond flour is roughly half fat and a fifth protein, none of it gluten-forming. It makes moist, dense, rich bakes and never a springy one; its fat means you can often reduce butter or oil slightly. Oat flour is starch-rich and absorbent, giving tender muffins and pancakes — check the label if you need it certified gluten-free, since oats are frequently cross-contaminated.
Commercial gluten-free blends mimic gluten with xanthan gum. They hydrate slowly, so batters improve with a 10-minute rest, and at 156 g per cup they are far heavier than wheat flour — one more reason to weigh rather than scoop when following a blend's "1:1" promise.
Swapping between neighbouring wheat flours works: bread for all-purpose gives a chewier result, all-purpose for cake flour a slightly sturdier one. To approximate cake flour from all-purpose, replace two tablespoons per cup with cornstarch and sift twice. To approximate bread flour, add one tablespoon of vital wheat gluten per cup of all-purpose.
Swapping across the gluten line does not work 1:1. Almond or oat flour in place of wheat flour needs a recipe built for it — more eggs or a binder, different liquid, different bake time. And never swap by volume across the table: 1 cup of semolina (167 g) is very nearly two cups of oat flour (95 g) by weight.
Protein. Bread flour runs 12–14%, all-purpose 10–12%. The extra protein forms a stronger gluten network that holds gas through long rises and gives chew — ideal for yeast bread, too tough for cake. You can swap them 1:1 in most recipes if you accept a chewier (bread flour) or softer (all-purpose) result.
Close enough for most cakes: for every cup (125 g) of all-purpose flour, remove 2 tablespoons and replace with 2 tablespoons (16 g) of cornstarch, then sift twice. The cornstarch dilutes the protein toward cake flour's 7–9%. It won't replicate the chlorination that lets true cake flour carry extra sugar and liquid.
It depends on the flour: cake flour 114 g, all-purpose 125 g, bread flour 130 g, whole wheat 120 g, almond 96 g, oat 95 g, gluten-free blend 156 g, semolina 167 g — all spooned and leveled. Scooping straight from the bag adds 20–30% to any of them.
On paper, slightly (13–14% vs 12–14%), but it bakes weaker. The bran in whole wheat flour cuts gluten strands during kneading, so loaves are denser and lower. Most whole-wheat breads blend in bread flour or add vital wheat gluten to compensate.