Can You Substitute Baking Soda for Baking Powder?

The answer

You cannot replace baking powder with the same amount of baking soda. King Arthur recommends, when you must replace 1 teaspoon of baking powder, combining 1/4 teaspoon baking soda with 1/2 teaspoon cream of tartar plus 1/4 teaspoon cornstarch or tapioca starch. The substitution changes the leavening system, so using the recipe’s original baking powder is still the more predictable choice.

Why

Baking powder is a prepared mixture that contains baking soda plus acidic ingredients, while baking soda is only sodium bicarbonate and needs acid from elsewhere in the recipe to generate the intended leavening reaction. King Arthur and Arm & Hammer both caution that the two should not be swapped one-for-one. King Arthur provides a baking-powder replacement based on baking soda, cream of tartar, and starch. Arm & Hammer similarly describes baking soda as substantially stronger than baking powder and gives an acid-containing substitution. Because acid balance also affects flavor and browning, a casual one-ingredient swap can change more than rise.

When it is usually OK

• You are replacing baking powder with a tested mixture that supplies both baking soda and an acid, such as cream of tartar.
• You measure the smaller baking-soda quantity accurately rather than using a one-for-one swap.
• The recipe can tolerate the slight differences that an emergency leavener substitution may produce.
• You understand that the replacement is for baking powder, not a general rule for changing every recipe’s leavening system.

When you should not

• You plan to replace 1 teaspoon of baking powder with 1 teaspoon of baking soda.
• The recipe lacks enough acid and you are using baking soda alone as the replacement.
• You are making a sensitive recipe where the exact rise, flavor, color, or pH balance is important and you can obtain the specified baking powder instead.
• You are changing other acidic ingredients at the same time without a tested formula.

Risks and exceptions

• Too much baking soda can leave an alkaline or soapy off-flavor and alter browning.
• Baking soda without sufficient acid may not produce the intended rise.
• Changing the acid-base balance can affect texture and flavor even if the baked good rises.
• A homemade substitution may not behave exactly like the double-acting baking powder used in many modern recipes.

Best practice

Use the leavener the recipe calls for whenever possible. If you are out of baking powder, use a tested substitution rather than guessing: King Arthur’s formula for 1 teaspoon baking powder is 1/4 teaspoon baking soda + 1/2 teaspoon cream of tartar + 1/4 teaspoon cornstarch or tapioca starch. Mix it evenly with the dry ingredients and bake according to the recipe.

Alternatives

• Buy or borrow baking powder and keep the original recipe unchanged
• Use a tested homemade baking powder made from baking soda, cream of tartar, and starch
• Choose another recipe designed around baking soda and the acids you already have
• Use a recipe-author-approved alternative leavener when one is specifically provided

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