Baking Soda and Baking Powder: What's the Difference?

You can't have one without the other, but they're not the same.

When it comes to baking powder and baking soda, you can't have one (powder) without the other (soda). But that doesn't mean they're interchangeable. Read on to learn the differences between baking soda and baking powder, why some recipes call for one – or both, and how to make substitutions if you run out of baking powder or baking soda.

What Is Baking Soda and What Does It Do?

Baking soda. Photo by Meredith_resized
Photo by Meredith.

Baking soda is another name for sodium bicarbonate. It's a leavening agent – a base that reacts when it comes into contact with an acid such as lemon juice, vinegar, or buttermilk (sometimes in such spectacular fashion that it's the basis for science fair projects). Reacting in baking means forming gas (CO2) bubbles, which is what helps cakes and cookies rise. When baking soda doesn't react with acid, it has a distinctive metallic taste. In other words, measure ingredients carefully to ensure you have enough baking soda and acid.

Another distinct property of baking soda is how quickly it reacts. That's good if you're assembling a model volcano, but less advantageous if you're trying to pull off a birthday cake. In that case, you want the rising to occur gradually over a longer period. That's where baking powder comes in.

What Is Baking Powder and What Does It Do?

Baking powder is another type of leavener used to aerate baked goods. It is made up of baking soda and a dry acid. When it comes into contact with liquid, gas (CO2) bubbles are released. Gas is released a second time when it is heated; hence the name "double acting" baking powder.

Baking powder. Photo by Meredith_resized
Photo by Meredith.

Is Baking Soda the Same As Baking Powder?

Although baking powder includes baking soda, the two are not the same. Baking powder also contains monocalcium phosphate and sodium acid pyrophosphate or sodium aluminum sulfate - dry acids that react with sodium bicarbonate (baking soda) when mixed with liquid and heat. So the process of creating air bubbles doesn't begin until the batter's mixed and heated in the oven.

Sometimes a recipe will call for both baking soda and baking powder. That's because after baking soda neutralizes the available acid, the pastry still needs a little more lift.

Baking Powder Substitute

It's important to remember that if you're out of baking powder, you can't use baking soda instead. But you can make your own baking powder: combine 2 tablespoons of baking soda with 1/4 cup of cream of tartar and pass it several times through a sifter. Some cooks believe the DIY baking powder mix tastes better than what's commercially available.

Baking Soda Substitute

Well, sort of. As we said, baking powder includes some baking soda. So if you run out of baking soda, but do have baking powder, you can increase the baking powder to approximate the effect of baking soda. So, if the recipe calls for 1/4 teaspoon of baking soda, substitute 1 teaspoon of baking powder. We're talking last resort here, but it should work.

How to Know If Your Baking Powder or Baking Soda Is Still Good

Has your baking powder or baking soda been sitting in the cupboard for a while? If so, it might not give your recipes the lift you're hoping for. Luckily there's a simple test to determine if they're still active.

  • To test if baking powder is still good, drop half a teaspoon into hot water. If it fizzes and forms bubbles, it's still good.
  • To test baking soda, drop half a teaspoon into a small amount of vinegar. If it fizzes, it's still active.

If you don't get any sort of reaction, it's time to toss that box and buy some new baking powder or baking soda.

Cookies Without Baking Soda

Run out of baking soda? These top-rated cookie recipes don't call for baking soda.

Cookies Without Baking Powder

No baking powder? These cookie recipes don't call for baking powder.

Cookies Without Baking Powder or Baking Soda

These top-rated cookie recipes get it done with no baking soda or baking powder.

More Baking Know-How:

Bookmark this list of common ingredient substitutions for when you run out of something in the middle of a recipe.

Get weight and volume conversions for everyday baking ingredients, and learn how using a scale makes you a better baker.

Are you a beginning baker? Here's how to stock your baking pantry.

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