Baking Soda and Baking Powder Calculator

Baking soda and baking powder both produce carbon dioxide bubbles to leaven baked goods, but they work differently and are not a 1:1 swap.

Baking soda (sodium bicarbonate) is pure base. It needs an acid already in the recipe to activate: buttermilk, yogurt, vinegar, lemon juice, brown sugar, or natural cocoa powder. With no acid it does not fizz at all, and what it leaves behind is a faintly soapy taste that people usually blame on the flour.

Baking powder is baking soda plus a dry acid (usually cream of tartar or sodium aluminum sulfate) plus cornstarch. It reacts in two stages: once when wet, again when heated. That is why it is called “double-acting.”

The conversion ratio: 1 tsp baking soda = 3 tsp baking powder

This means baking soda is about three times as powerful per teaspoon. Most recipes call for more baking powder than soda because the combined leavener in powder is diluted.

Substituting soda for powder: Divide the baking powder amount by 3 to get baking soda. But you now have no acid source. Add 1/2 tsp cream of tartar per 1/4 tsp baking soda, or use buttermilk in place of regular milk.

Substituting powder for soda: Multiply the baking soda amount by 3. If the recipe had an acid in it, swap that for something neutral (milk in place of buttermilk, water in place of vinegar), because the powder brings its own acid and the leftover one has nothing to react with. The result tastes less tangy, which is sometimes an improvement and sometimes the whole point of the original recipe.

Recipes that call for both: some recipes use a small amount of soda to neutralize excess acid (giving a milder flavor) while baking powder handles the majority of leavening. This is intentional and common in chocolate cake recipes.