Baking
Cake Flour
Cake flour's hub page centers on its unusually low protein content (roughly 7-9%) and correspondingly light 114g-per-cup weight — the lightest of the standard wheat flours on this site — both a direct result of being milled from soft wheat specifically to minimize gluten formation rather than build it.
The most practical connection this page makes is to the all-purpose-flour substitutes page, since cake flour doesn't have its own substitutes entry — instead, this site documents the reverse relationship: how to approximate cake flour FROM all-purpose flour (minus 2 tablespoons per cup, plus 2 tablespoons cornstarch), a genuinely common kitchen need when a recipe calls for cake flour and only all-purpose is on hand.
US cake flour is also typically chlorinated, a processing detail that weakens starch and adds slight acidity to help a batter set into a finer, more tender crumb — worth knowing since it's part of why cake flour isn't simply "weaker" all-purpose flour, but a genuinely differently processed product.
Cake flour is milled from soft wheat and chlorinated in a process that further weakens gluten formation beyond what the lower protein content alone would achieve — that combination is exactly why cake flour produces the notably tender, fine crumb associated with a classic layer cake, a texture all-purpose flour can't fully replicate.
Chiffon cake and angel food cake recipes lean especially heavily on cake flour's low protein content, since both depend on whipped egg structure for their rise and can't afford the toughening effect a stronger, higher-protein flour would introduce into that delicate foam.
Boxed cake mixes are formulated around this same lower-protein profile, which is part of why they reliably produce a noticeably more tender crumb than a from-scratch cake made with standard all-purpose flour, independent of any other ingredient or technique difference.
Cake flour's chlorination process, developed in the 20th century, was a specific industrial innovation aimed at replicating and standardizing the softer, more delicate texture that lower-protein, more finely milled flour could achieve for cake baking specifically.
Sponge cake and genoise recipes, particularly finicky about flour weight and protein content, are often cited as the baked goods most sensitive to the cake-flour-versus-all-purpose distinction, since their delicate structure has the least margin for a heavier, more structured crumb.
Swans Down and Softasilk are two long-standing US cake flour brands, both marketed specifically around the fine, low-protein milling that distinguishes cake flour from a general-purpose flour on the same grocery shelf.
Frequently asked questions
Why is cake flour so much lighter per cup than all-purpose flour?
It's milled from soft, low-protein wheat and ground extremely fine, and that combination packs less mass into the same spooned-and-leveled cup than all-purpose flour's coarser, higher-protein structure.
How do I substitute for cake flour if I don't have any?
Use 1 cup all-purpose flour minus 2 tablespoons, plus 2 tablespoons cornstarch, per cup of cake flour called for — this lowers the effective protein content to approximate cake flour's tenderness.
Is cake flour the same as self-rising flour?
No — cake flour has no leavening added; self-rising flour is regular flour with baking powder and salt already mixed in, a genuinely different modification solving a different problem.
Does bleaching change how cake flour performs?
Yes, slightly — the chlorination process weakens starch and adds a touch of acidity that helps batters set with a finer crumb, an assist unbleached cake flour's low protein alone doesn't provide.
Where can I find this site's cup-to-gram conversion for cake flour?
The dedicated Convert page for cake flour has the full breakdown by cup, tablespoon, teaspoon, and gram, alongside the same substitution guidance summarized here.