The simple answer is yes. However, there are several caveats you have to consider. Swapping these two ingredients can be disastrous, but it is possible—as long as you’re precise with your measurements. Because their chemical composition is different, substituting is not a direct one-to-one conversion.
If your recipe asks for baking soda but you only have baking powder, the pros at Masterclass strongly suggest you remember the former is a stronger leavening agent, so you’ll need about three times the amount of baking powder as you would baking soda. For example, if a recipe calls for one teaspoon of baking soda, try substituting with three teaspoons of baking powder. The downside to this is that if the measurements are off, you’ll have a very bitter pastry on your hands.
On the flip side, if you’re trying to replace baking powder with baking soda, not only do you have to remember to put less baking soda than you would powder, but you also have to keep in mind that you must add an acid to the recipe—buttermilk, honey, etc. Failure to do so will result in metallic-tasting, dense and hard baked goods. Arm and Hammer recommends that for every teaspoon of baking powder you use ¼ baking soda instead, plus ½ teaspoon of cream of tartar. No cream of tartar? No problem. Here are six more substitutes for baking powder that are just as good as the real thing.