Whisk 3/4 cup plus 2 tablespoons all-purpose flour with 2 tablespoons cornstarch and use it in place of 1 cup cake flour. Without cornstarch, use 1 cup minus 2 tablespoons sifted all-purpose flour.
Ratios from university extension services and King Arthur Baking. Checked .
Cake flour substitutes, best first
- For 1 cup cake flour3/4 cup + 2 Tbsp (105 g) all-purpose flour + 2 Tbsp (14 g) cornstarch, whiskedBest for: layer cakes, cupcakes
King Arthur; swap by equal weight or volume.
- For 1 cup sifted cake flour1 cup minus 2 Tbsp (7/8 cup) sifted all-purpose flourBest for: cakes when you have no cornstarch
Utah State, NMSU, Nebraska, UC.
Why the swaps work
Cake flour has less protein (King Arthur: about 10% vs 11.7% for its all-purpose), so it forms less gluten and gives a softer, finer crumb. Cornstarch dilutes all-purpose flour's protein.
Questions people ask
Can I use all-purpose flour instead of cake flour?
Yes: use 2 Tbsp less per cup, or replace 2 Tbsp of it with cornstarch for a more tender cake.
Why is cake flour better for cakes?
Its lower protein means less gluten, so cakes come out softer and more tender.