How to Make All-Purpose Flour into Self-Rising Flour?

For 1 cup all-purpose flour, add 1 1/2 teaspoons baking powder and 1/4 teaspoon salt

For 2 cups all-purpose flour, add 3 teaspoons baking powder and 1/2 teaspoon salt

For 3 cups all-purpose flour, add 1 tablespoon plus 1 1/2 teaspoons baking powder and 3/4 teaspoon salt

For 4 cups all-purpose flour, add 2 tablespoons baking powder and 1 teaspoon salt

Whisk thoroughly to combine

Use immediately or store in an airtight container