How to Make Your Own Baking Powder
If you have ever made snicker-doodles (these are a favorite of ours) or play-dough (I need to add this to my to do list), then I am sure you have the needed ingredient for baking powder ... cream of tartar which is the powdered form of tartaric acid (an organic acid found in plants).
Homemade Baking Powder
2 parts cream of tartar
1 part baking soda
1 part cornstarch (optional)
Place all ingredients in and whisk until combined. Store in an air-tight container.
Easy-Peasy! I made my first batch of homemade baking powder a few months ago and am just now running low. Since I have just recycled an old baking powder container (8.1 oz), the amounts of 1/2 cup of cream of tartar and 1/4 cup of baking soda and 1/4 cup of cornstarch would about fill it perfectly. The only change I have noticed while using homemade baking powder is in how our pancakes will rise while cooking, but no noticeable change in taste. I have also used it in all of my other baking and have seen no major difference as well!
Cost Comparison: without doing the math (I'm off duty right now, heehee) I'd have to say homemade and store bought are very comparable in price
If you are need of a little science/chemistry lesson check out this link! Great explanation of the need for an acid (cream of tartar) and base (baking soda) to create a foaming action that is known as our leavening (or raising) agent in our baking!