Baking Soda vs. Baking Powder: How Chemical Leaveners Work and When to Use Each

Baking soda and baking powder sit side by side in most pantries, look almost identical and both make baked goods rise. Yet they are not interchangeable, and confusing them can lead to flat pancakes, bitter muffins or cakes with a strange metallic taste. Understanding how these two chemical leaveners work explains why some recipes call for one, some for the other and many for both. It also helps you make smart substitutions, keep your leaveners fresh and fix common baking problems. This guide explains the chemistry in plain language.

What leavening means

To leaven means to make dough or batter rise by filling it with gas. That gas expands when heated, making baked goods light and airy. There are three main ways to leaven baked goods:

• Biological leavening: Yeast and sourdough cultures produce carbon dioxide through fermentation.
• Mechanical leavening: Air is incorporated by beating eggs, whipping cream or creaming butter and sugar. Steam from water in the dough also expands in the oven, as in puff pastry and popovers.
• Chemical leavening: Baking soda and baking powder produce carbon dioxide through chemical reactions.

Chemical leaveners are fast. They work within minutes, which is why quick breads, pancakes, muffins, biscuits, cakes and cookies can be made without waiting for yeast.

Baking soda: a base that needs acid

Baking soda is sodium bicarbonate, a pure alkaline compound. When it comes into contact with an acid and moisture, it reacts immediately, producing carbon dioxide gas, water and a salt.

Because baking soda needs acid to react, recipes that use it always include an acidic ingredient, such as:

• Buttermilk, yogurt or sour cream.
• Brown sugar, molasses or honey.
• Natural, non-alkalized cocoa powder.
• Lemon juice, vinegar or orange juice.
• Applesauce, bananas or pumpkin puree, which are mildly acidic.
• Chocolate.

Baking soda is very strong. Only a small amount, often 1/4 to 1/2 teaspoon per cup of flour, is needed. Too much baking soda leaves an unpleasant soapy, metallic taste, because there is not enough acid to neutralize it.

Baking soda and browning

Besides leavening, baking soda raises the pH of a dough or batter, making it more alkaline. This speeds up the Maillard reaction, so baked goods brown more. It also weakens gluten slightly, making cookies spread more and giving a more tender, coarser crumb. That is why many chocolate chip cookie recipes use baking soda: it helps produce golden, chewy cookies.

Baking powder: a complete leavener in a can

Baking powder contains baking soda plus one or more dry acids, along with cornstarch to absorb moisture and keep the ingredients from reacting in the can. Because it contains both base and acid, baking powder only needs moisture and, in many cases, heat to react. It can leaven recipes that do not contain acidic ingredients, such as those made with plain milk.

Most baking powder sold today is double-acting:

1. First action: A fast-acting acid reacts with baking soda as soon as liquid is added, producing some gas in the batter.
2. Second action: A slow-acting acid reacts only when the batter is heated in the oven, producing more gas as the baked goods rise and set.

This two-stage release gives bakers flexibility. Batter can sit for a short time before baking without losing all its rising power.

A typical amount is about 1 to 1½ teaspoons of baking powder per cup of flour.

Why some recipes use both

Many recipes, such as buttermilk pancakes, cakes and some cookies, use both baking soda and baking powder. There are several reasons:

• To neutralize acid: When a recipe contains acidic ingredients like buttermilk, baking soda neutralizes some of the acid, balancing the flavor and preventing a sour taste.
• To add extra lift: Baking soda alone may not provide enough leavening if the amount of acid is limited. Baking powder adds additional, reliable rise.
• To control browning and texture: Baking soda increases browning and spreading, while baking powder provides lift without making the batter too alkaline.

Comparing the two

Timing matters

Because baking soda reacts immediately, batters made only with baking soda should be baked soon after mixing. If they sit too long, the gas escapes and the baked goods may be flat. Double-acting baking powder is more forgiving because part of the reaction happens in the oven. Still, for the best results, mix wet and dry ingredients just before baking and get the batter into a preheated oven quickly.

How to test freshness

Leaveners lose their strength over time, especially when exposed to moisture and humidity. Old leaveners are a common cause of flat cakes and dense muffins.

• Testing baking soda: Add 1/4 teaspoon of baking soda to a tablespoon of vinegar or lemon juice. It should bubble vigorously right away.
• Testing baking powder: Add 1/2 teaspoon of baking powder to a few tablespoons of hot water. It should fizz strongly.

If there is little or no reaction, replace the leavener. Store both in tightly closed containers in a cool, dry place. Baking powder generally stays effective for about 6 to 12 months after opening; baking soda lasts longer but can still lose strength.

Substitutions

Substituting one for the other is possible in an emergency, but it requires adjustments.

Replacing baking powder with baking soda

You need an acid. For each teaspoon of baking powder, use about 1/4 teaspoon of baking soda plus an acid, such as 1/2 teaspoon of cream of tartar or replacing some of the milk with buttermilk or yogurt.

Replacing baking soda with baking powder

Use about three times as much baking powder as the recipe's baking soda. For example, replace 1/2 teaspoon of baking soda with about 1½ teaspoons of baking powder. The baked goods may taste slightly more acidic and brown less, and the texture may be a little different.

Homemade baking powder

Mix 1 part baking soda with 2 parts cream of tartar. For example, 1/4 teaspoon of baking soda plus 1/2 teaspoon of cream of tartar replaces 1 teaspoon of baking powder. Homemade baking powder is single-acting, so bake immediately after mixing. Add a little cornstarch if you want to store it.

Signs of too much or too little leavening

• Too much leavening: Baked goods rise quickly and then collapse, have a coarse, crumbly texture or large holes, and may taste soapy, salty or metallic. Cookies may spread excessively and brown too much.
• Too little leavening: Baked goods are dense, heavy and do not rise properly. Pancakes are flat and gummy.

Measure leaveners carefully with level spoons. A heaping teaspoon can contain twice the intended amount.

Leavening and cocoa

Cocoa powder comes in two main types, and they interact differently with leaveners:

• Natural cocoa powder is acidic and is often paired with baking soda. It gives a lighter, reddish-brown color and a fruity chocolate flavor.
• Dutch-process cocoa powder has been treated to neutralize its acidity. It is often paired with baking powder and gives a darker color and smoother, mellower flavor.

Swapping one for the other in a recipe can affect rise, color and flavor, especially when the recipe relies on cocoa for its acid.

Other leaveners you may meet

Some traditional recipes use leaveners that are less common today. Baker's ammonia, or ammonium carbonate, was used before baking powder was widely available and is still used in some Scandinavian and German cookies and crackers. It produces very crisp, light results, but it releases a strong ammonia smell during baking, so it only suits thin, dry baked goods from which the gas can escape completely. Cream of tartar, a by-product of winemaking, is an acid used with baking soda and also stabilizes whipped egg whites. Self-rising flour already contains baking powder and salt; if you use it in a recipe written for all-purpose flour, leave out the added baking powder and salt.

Frequently asked questions

Can I use baking soda instead of baking powder? Only if you add an acid, such as cream of tartar, buttermilk or yogurt. Use about one quarter of the amount of baking soda.

Why do my muffins taste bitter or soapy? There may be too much baking soda, or not enough acid to neutralize it. Measure carefully and check the recipe.

What is double-acting baking powder? Baking powder that reacts twice: once when mixed with liquid and again when heated in the oven.

How long do baking soda and baking powder last? Baking powder usually stays effective for 6 to 12 months after opening. Test both before using them if they are old.

Why do recipes tell me to mix dry ingredients separately? To distribute the leavener evenly throughout the flour, so that the baked goods rise uniformly without pockets of bitter baking soda.

The bottom line

Baking soda and baking powder both create carbon dioxide gas to make baked goods rise, but they work differently. Baking soda is a strong base that needs an acid in the recipe and also increases browning and spread. Baking powder contains its own acid, needs only moisture and heat, and provides reliable lift in recipes without acidic ingredients. Many recipes use both for balance. Measure carefully, keep leaveners fresh and test them when in doubt, and you will enjoy light, tender, perfectly risen baked goods every time.