Let’s break it down without the chemistry degree. Plain flour is just flour—pure, neutral, and ready to be bossed around by your recipe. Self-raising flour, on the other hand, has baking powder and a little salt already mixed in. It’s like the over-caffeinated cousin of plain flour that can’t sit still.
That means self-raising flour will make your batter puff up on its own, even if the recipe doesn’t call for extra leavening. If you use it in a cookie recipe that requires zero rise, you might get fluffy muffins instead of chewy cookies. Disaster? Not quite. Different? Absolutely.
Your muffins, scones, and quick breads will actually love self-raising flour. But if you’re making something delicate—like a flour tortilla, a pie crust, or a classic shortbread—you’re heading for a texture tragedy.
Plain vs Self-Raising Flour: The Difference & Magic Ratio
So, how do you swap without ruining dinner?
Here’s the golden rule: if your recipe uses baking powder anyway, you can usually substitute self-raising flour one-for-one. Just remove the baking powder the recipe calls for. Easy, right? But wait—your recipe probably doesn’t use the exact same amount of baking powder as what’s in the self-raising flour.
Most self-raising flours contain about 1½ teaspoons of baking powder per cup (roughly 125 grams). So if your recipe calls for 1 cup of plain flour plus 1 teaspoon of baking powder, you’re fine. If it calls for 2 teaspoons of baking powder per cup? You’ll get a volcano. Your cake will rise, crack, and possibly escape the pan.
So here’s what I do (and you should too): subtract the baking powder from the recipe. If the recipe also calls for salt, reduce that too, because self-raising flour already has a pinch. Your cake won’t taste salty—but your pretzels might.
