How much baking powder to one cup of plain flour make it the same as self raising flour?

To make one cup of plain flour into self-raising flour, you'll need to add 2 teaspoons of baking powder.

Here's why:

* Self-raising flour already contains baking powder. It's a combination of plain flour and baking powder, making it easier to bake cakes, biscuits, and other quick breads.

* The ratio of baking powder to plain flour in self-raising flour is typically 2 teaspoons per cup. This is the standard ratio used in most self-raising flour brands.

Important Note: Always check the instructions on your recipe as they may vary slightly. Some recipes might require a slightly different amount of baking powder based on other ingredients.