Step 1

Per one teaspoon of baking powder asked for in a recipe, you’ll need: 1/2 teaspoon cream of tartar and 1/4 level teaspoon bicarbonate of soda (baking soda)

Step 2

Mix the cream of tartar and baking soda in a small bowl. Optionally add cornstarch (or arrowroot powder) if you aren't using it immediately to stop the two ingredients from reacting/clumping and to extend the shelf-life.

Step 3

Either use it immediately or transfer it to a small airtight container.Note: homemade baking powder substitute won't be "double-acting," so be quick to get your bake into the oven after adding the powder to your batter/dough.

Step 4

You can achieve the same effect by combining baking soda with another acid. For example:Instead of 1 teaspoon baking powder: use ¼ teaspoon baking soda + ½ cup buttermilk.Simply use the buttermilk in place of other liquids in the batter. Obviously, this method only works with recipes that contain lots of liquid in the batter.