Everything you need to know about the difference between baking soda and baking powder. Plus, helpful tips for substitutions, how to test them for freshness, and so much more!

A box of baking soda and can of baking powder on top of a marble surface.

Have you ever wondered what in the world is the difference between baking soda and baking powder? While the two have similar names, they are actually quite different! 

Since they’re commonly used in baking, it’s good to understand the difference between them. So today, I’m sharing everything you need to know about these two ingredients, including how to use them in recipes, how you test them to see if they’re still fresh, and how to substitute one for the other!

If you love the science behind baking, this is one post that I think you’ll find incredibly helpful!

A box of baking soda behind a measuring spoon on top of a marble surface.

What Is Baking Soda?

Baking soda, also known as sodium bicarbonate or bicarbonate of soda, is a chemical compound that when mixed with an acid creates carbon dioxide. When baking soda is combined with an acid in baked goods, the small bubbles from the carbon dioxide gas are trapped inside the batter and that’s what helps them rise.

In other words, when it’s combined with an acidic ingredient in baking it helps to lift baked goods. Some common acidic ingredients that you’ll see used alongside baking soda are lemon juice, vinegar, buttermilk, brown sugar, sour cream, or molasses.

Keep in mind that if you use too much baking soda in a recipe or there’s not enough acid in your batter, the finished product can have a metallic taste. Baking soda also helps to create a beautiful brown color on baked goods like homemade pancakes.

How much should you use in a recipe?

The amount you’ll want to use will vary depending on the recipe, but a good rule of thumb is to use about 1/4 teaspoon per cup of flour.

How do you tell if it’s still fresh? 

To test your baking soda, add 1/4 teaspoon to 1 tablespoon of fresh lemon juice or vinegar. If the mixture bubbles vigorously it’s still good to use.  

A can of baking powder behind a measuring spoon sitting on top of a marble surface.

What Is Baking Powder? 

Is baking powder the same as baking soda? Well, baking powder is actually made from baking soda. Wait, what?! Let me explain.

Baking powder is made from a mixture of baking soda, cream of tartar (which is a dry acid), as well as a little cornstarch to help keep the two from reacting. Unlike baking soda, baking powder doesn’t need an acidic ingredient in the recipe for it to work. Since it already has an acidic ingredient mixed with it, all you have to do is add liquid and the baking powder goes to work. 

There are also two types of baking powder, single-acting and double-acting. Single-acting baking powder reacts fully once you combine it with a liquid. However, the most commonly used baking powder is double-acting. Double-acting baking powder works in two stages, once when you combine it with a liquid and then again as it’s heated. 

How much should you use in a recipe? 

Since baking powder is made from a combination of ingredients, it’s not quite as strong as baking soda. In fact, baking soda is about 3-4x more powerful than baking powder. A good rule of thumb is to use 1 teaspoon of baking powder per cup of flour. 

How do you tell if it’s still fresh? 

Add 1/4 teaspoon of baking powder to 1 tablespoon of hot water, if the mixture bubbles then your baking powder is still good to use.

A box of baking soda, can of baking powder, and measuring spoons sitting on top of a marble surface with a white napkin on the side.

Frequently Asked Questions

Why do some recipes use both? 

The short answer for this is because the recipe probably has a little bit of an acidic ingredient, but when combined with baking soda, it doesn’t create enough carbon dioxide to fully lift the baked good. Because of this, baking powder is also added to help add the extra lift you want in your baked good.

What’s a good sub for baking powder? 

If you don’t have any on hand, you can make your own by using a 2:1 ratio of cream of tartar to baking soda. In other words, if you have a recipe that calls for 1 and 1/2 teaspoons of baking powder you can combine 1 teaspoon cream of tartar with 1/2 teaspoon baking soda to make 1 and 1/2 teaspoons of baking powder. If you use this substitute, you will need to use it immediately in your recipe.

What’s a good sub for baking soda? 

Since baking soda is 3 to 4 times more powerful than baking powder, it’s really best to stick with baking soda in your recipe. However, in a pinch, you can use baking powder in place of baking soda. For instance, if your recipe calls for 1/4 teaspoon baking soda you should be able to substitute it with 1 teaspoon of baking powder.

How often should you replace them?

If stored in a cool, dry place, they should stay fresh for up to 6 months or even longer. I actually prefer to replace mine about every 3 months to ensure that they’re fresh. 

Hopefully this post helps answer any questions you may have about these two ingredients. If you have any other questions, feel free to leave them in the comments!