Baking Soda vs Baking Powder: Difference and Swaps

The short version

	Baking soda	Baking powder
What it is	Sodium bicarbonate, a base	Baking soda plus powdered acid and cornstarch
Needs an acid in the recipe	Yes	No, it carries its own
When it makes gas	As soon as it meets the acid and liquid	Double-acting: when wet, again when heated
Acid partners	Buttermilk, yogurt, brown sugar, lemon juice, vinegar	Not needed

Both are measured in small amounts with level measuring spoons; K-State's measuring guide lists baking soda among the ingredients that are usually measured with spoons rather than cups. The cooking measurement converter turns teaspoons into milliliters or tablespoons when a recipe mixes units.

Baking soda: a base that needs an acid

Baking soda is sodium bicarbonate. University of Illinois Extension describes it as a base on the pH scale, and K-State Research and Extension explains that it reacts with an acid to release carbon dioxide gas. That gas is what makes the batter rise.

Without an acid, soda has nothing to react with. That is why recipes that use soda alone also contain an acidic ingredient. Illinois Extension names vinegar, buttermilk, brown sugar, yogurt and lemon juice as examples. If you see buttermilk pancakes or a cake with yogurt and only baking soda in the list, the acid is already there.

Baking powder: soda with the acid built in

Baking powder contains baking soda plus one or more powdered acids, and cornstarch. Illinois Extension lists cream of tartar and cornstarch; K-State calls it a mixture of baking soda and powdered acids. Because the acid is in the can, baking powder works in recipes that have no acidic ingredient of their own.

Most baking powder is double-acting. K-State describes the two stages: the first rise starts when the wet ingredients are added, and the second when another powdered acid reacts with the remaining soda once the batter is heated above 170°F. K-State also notes that single-acting powders exist and rise only once.

Out of baking powder: make it from soda

Baking powder is soda plus acid, so you can rebuild it with baking soda and cream of tartar, which K-State identifies as an acid and one of the powdered acids used in baking powder. K-State also notes that it is a byproduct of wine production. Illinois Extension and K-State give the same ratio, and Nebraska Extension a slightly more acidic one:

Replace 1 teaspoon of baking powder

1/4 tsp baking soda + 1/2 tsp cream of tartar

Recipe needs	Baking soda	Cream of tartar	Nebraska version
1/4 tsp powder	1/16 tsp	1/8 tsp	3/16 tsp
1/2 tsp powder	1/8 tsp	1/4 tsp	5/16 tsp
1 tsp powder	1/4 tsp	1/2 tsp	5/8 tsp
1 1/2 tsp powder	3/8 tsp	3/4 tsp	15/16 tsp
2 tsp powder	1/2 tsp	1 tsp	1 1/4 tsp
1 tbsp powder	3/4 tsp	1 1/2 tsp	1 7/8 tsp
4 tsp powder	1 tsp	2 tsp	2 1/2 tsp

The Nebraska column is the cream of tartar amount from its substitution table, used with the same amount of soda. Illinois Extension warns that the swap won't be perfect. One likely reason follows from K-State's description of double-acting powder: the homemade mix has only the one acid, so it lacks the second, heat-triggered stage. K-State also lists 1/4 teaspoon of cornstarch as an optional third part.

The buttermilk route

If you have baking soda but no cream of tartar, K-State gives another option for each teaspoon of baking powder: 1/4 teaspoon of baking soda plus 1/2 cup of buttermilk, sour milk or yogurt, with the liquid in the recipe reduced to make room for it. The acid then comes from the dairy. If you have no buttermilk either, Nebraska Extension makes it from 1 tablespoon of lemon juice or vinegar plus enough milk to make 1 cup, left to stand for 5 minutes.

Out of baking soda: use more powder

Going the other way, Illinois Extension says to triple the amount: use three times as much baking powder as the baking soda the recipe asks for.

Recipe needs	Baking powder instead
1/4 tsp soda	3/4 tsp
1/2 tsp soda	1 1/2 tsp
1 tsp soda	1 tbsp
1 1/2 tsp soda	4 1/2 tsp
2 tsp soda	2 tbsp

Tripling the powder also adds its own acid and cornstarch to the recipe, on top of the acidic ingredient the soda was meant to react with, so the swap is a fallback rather than an exact match.

Worked examples

Pancakes that need 2 teaspoons of baking powder

With soda and cream of tartar on hand: 1/2 teaspoon of baking soda and 1 teaspoon of cream of tartar, or 1 1/4 teaspoons of cream of tartar by the Nebraska ratio.

A quick bread that needs 1 teaspoon of baking soda

With only baking powder: 1 × 3 = 1 tbsp of baking powder. Since 3 teaspoons make a tablespoon, that is one level tablespoon.

Scaling a recipe that uses both

A cake with 1.5 teaspoons of baking powder, made at double size, needs 1 tbsp of baking powder. The recipe scaler multiplies the leaveners with everything else and shows kitchen fractions. Leavening is one of the things that changes at high elevation; the guide to high altitude cooking and baking has Colorado State University Extension's baking powder adjustments by elevation.

Is it still fresh?

K-State gives two quick checks for whether a box still works:

Baking soda: stir 1 1/2 teaspoons into 1 tablespoon of vinegar. If it fizzes, it is still usable.
Baking powder: stir 1 teaspoon into 1 tablespoon of warm water. If it does not fizz, it is no longer active and should be thrown out.

The baking powder test uses plain water because the powder carries its own acid. The soda test needs vinegar for the same reason it needs an acid in a recipe.

Measuring small amounts

Because the amounts are small, a heaped spoon makes a large difference in percentage terms. Level each spoon with a straight edge, as K-State advises for dry ingredients. For flour and sugar, which are measured in cups, the cups to grams converter gives the weights, which is more repeatable than a cup. Spoon sizes for metric recipes are covered in US cup vs metric cup.

Frequently asked questions

What is the difference between baking soda and baking powder?

Baking soda is pure sodium bicarbonate, a base that needs an acid in the recipe to release carbon dioxide. Baking powder is baking soda already mixed with a powdered acid and cornstarch, so it only needs liquid, and most of it is double-acting: it releases gas once when wet and again in the oven.

Can I use baking powder instead of baking soda?

Yes, with more of it. University of Illinois Extension says to use three times as much baking powder as the baking soda called for, so 1 teaspoon of soda becomes 1 tablespoon of baking powder. The result will not be identical, because the powder brings its own acid as well.

Can I use baking soda instead of baking powder?

Only together with an acid. For each teaspoon of baking powder, use 1/4 teaspoon of baking soda and 1/2 teaspoon of cream of tartar, the ratio given by both Illinois and K-State extension. Nebraska Extension gives 5/8 teaspoon of cream of tartar instead.

What does double-acting mean?

Double-acting baking powder releases gas in two stages. K-State Research and Extension explains that the first rise starts when the wet ingredients go in and the second happens when a second powdered acid reacts with the remaining soda once the batter is heated above 170°F.

How do I know if baking soda or baking powder is still good?

K-State gives two quick tests. Stir 1 1/2 teaspoons of baking soda into 1 tablespoon of vinegar; if it fizzes it still works. Stir 1 teaspoon of baking powder into 1 tablespoon of warm water; if it does not fizz, throw it out.

Sources

Written by Tobias. Updated November 2, 2026.