Use ⅓ teaspoon of baking soda for every 1 teaspoon of baking powder called for in the recipe.
Baking Powder Substitute With Cream of Tartar:
Combine ⅓ teaspoon of baking soda and ⅔ teaspoon of cream of tartar to substitute for 1 teaspoon of baking powder.
Notes
To increase the cream of tartar baking powder substitute:
For 2 teaspoons baking powder: ⅔ teaspoon baking soda plus 1 ⅓ teaspoon cream of tartar
For 1 tablespoon baking powder: 1 teaspoon baking soda plus 2 teaspoons cream of tartar
To substitute baking powder for baking soda:Using baking powder instead of baking soda is trickier. That’s because you would need to use 3 times as much baking powder to get the same rising effect; you could end up with a bitter, chemical taste if you add too much leavening.
If you need 1 teaspoon of baking soda, then go for 1 tablespoon baking powder.
If the recipe calls for more than 1 teaspoon baking soda, you may want to wait for another time.