Baking Powder vs. Baking Soda: What's the Difference?

While baking soda and baking powder are used in small amounts, these leavening agents are both essential to help your baked goods rise to the occasion. However, when comparing baking soda vs. baking powder, the key properties of the two ingredients are different. So, what is the difference between baking soda and baking powder? And what does baking soda do that baking powder doesn't? Read on for the scoop from our Test Kitchen pros.

How to Test Baking Soda for Freshness

Similar to how inactive yeast cannot make bread recipes rise, baking soda can only achieve its purpose if it's fresh. To test baking soda's effectiveness, add ½ teaspoon baking soda in a small bowl and top with 2 teaspoons of distilled vinegar. If the baking soda bubbles immediately, you're good to go. If the mixture sits fairly still, toss your baking soda and invest in a new box.

What Is Baking Powder?

It's important to understand baking powder's powers to compare and contrast baking soda vs. baking powder. Baking powder combines baking soda, some acid, and some anti-caking agent (like cornstarch). Baking powder harnesses the powers of both an acid and a base, so recipes that call for baking powder don't necessarily require an acid to work. Recipes with baking powder simply need heat and moisture to rise as desired.

Most commercial baking powders sold in America are "double acting." The first reaction happens when the baking powder is combined with a liquid, which begins to aerate the mixture. The second reaction occurs in the oven under the influence of heat. The acidic element of baking powder (cream of tartar or something similar) weakens the gluten within the dough or batter, yielding a whiter, more delicate, and usually tighter texture than if you used both baking soda and powder.

How to Test Baking Powder for Freshness

To test baking powder for freshness, add 1 teaspoon of baking powder in a small bowl, then top with 1 cup of hot water. If the mixture bubbles, the baking powder is fresh enough to use. If the mixture is still, throw it away and refresh your pantry with a new box.

Why Some Recipes Call for Both Baking Powder and Baking Soda

Some recipes require more leavening than the amount of straight acid (baking soda) the batter or dough can handle. That's when baking powder is beneficial—it creates even more lift for your buttermilk pancakes.

Some baking recipes call for neither baking soda nor baking powder. This is usually the case when either:

• Yeast acts as the leaven
• The process of making the batter or dough includes whipping in plenty of air.
• The baked good is designed to be more creamy in texture, such as a custard or crème brûlée

What Is the Difference Between Baking Soda vs. Baking Powder—and What Are the Similarities?

So is baking powder the same as baking soda? No, but they do overlap in terms of ingredients and purpose. Baking soda and baking powder both contain sodium bicarbonate. In combination with an acid, either already in the baking powder or added in the recipe alongside baking soda, this creates carbon dioxide gas that acts as a framework to create a tall and lofty texture.

Can I Use Baking Powder Instead of Baking Soda?

The ingredients are not interchangeable for the reasons mentioned above. But in addition to leavening, they're both formulated to:

• Create tenderness—The gases expand, and cell walls within baked goods begin to stretch and thin, resulting in a tender texture that is less dense and easier to eat.
• Improve flavor—Synthetic leavens, in proper proportion, can lend a salty and/or sour flavor that's signature in scones, biscuits, and soda bread.

Both are affordable and don't take up a lot of pantry staple storage space, so we recommend having both baking powder and baking soda on hand.

The Bottom Line About Baking Soda vs. Baking Powder

Purchase baking soda and baking powder in as small of boxes and canisters as you can find, then store them in a cool, dry place. Replace every six to 12 months, and test for freshness each use beyond three months.

If your baking recipe calls for both baking soda and baking powder and you don't have either, consider swapping in self-rising flour for the all-purpose flour in the recipe. Self-rising flour contains flour, salt, and baking powder, and it can act as a one-for-one replacement for the all-purpose flour called for in a recipe.