Baking soda is a pure base that needs an acid in the recipe to make it rise; baking powder is baking soda pre-mixed with its own acid. You can substitute baking powder for baking soda, but you need 3 teaspoons of powder for every 1 teaspoon of soda, and the flavor may turn slightly bitter.
Key facts
- Baking soda is sodium bicarbonate, a base with a pH of about 8 (King Arthur Baking).
- Baking powder already contains soda plus an acid, so it works without buttermilk, yogurt or another acidic ingredient.
- Most store-bought powder is double-acting: it reacts once when wet and again in the oven's heat.
- To replace 1 tsp baking soda, use 3 tsp (1 tbsp) baking powder.
- To replace 1 tsp baking powder, use 1/4 tsp baking soda plus 1/2 tsp cream of tartar.
- Iowa State University Extension puts best quality at about 6 months for each.
What is the difference between baking soda and baking powder?
Both are chemical leaveners. They make carbon dioxide bubbles that get trapped in batter or dough and expand in the oven, so cakes, muffins, pancakes and biscuits rise without yeast. The difference is what each one needs to do that job.
Baking soda (sodium bicarbonate) is a base. On its own, stirred into a neutral batter, it does very little. It reacts when it meets an acid, such as buttermilk, yogurt, sour cream, brown sugar, molasses, lemon juice or vinegar. That reaction starts the moment the wet and dry ingredients meet, so soda-leavened batters should go into the oven promptly.
Baking powder is a complete leavening system in one can. King Arthur Baking describes it as baking soda combined with a dry acid (cream of tartar in the simplest version); commercial blends also contain starch.
| Baking soda | Baking powder | |
|---|---|---|
| What it is | Sodium bicarbonate (a base) | Baking soda + dry acid + starch |
| Needs an acid in the recipe? | Yes | No |
| When it reacts | As soon as it's wet and meets acid | Double-acting: when wet, then again with heat |
| Relative strength | About 3 times stronger | Use 3 tsp to replace 1 tsp soda |
| Freshness test | 1 tsp in 3 tbsp vinegar | 1 tsp in 1/3 cup hot water |
How do baking soda and baking powder work?
The basic chemistry is the same in both: acid plus base, with water, makes carbon dioxide gas. What changes is where the acid comes from and when the reaction happens.
Baking soda: base meets acid
With soda, the acid comes from your other ingredients. That is why recipes that call for buttermilk or yogurt so often call for baking soda too. The soda lifts the batter and also neutralizes some of the acid, which takes the sharp, tangy edge off the finished bake.
Double-acting baking powder
Double-acting powder releases gas in two stages. A first round of bubbles forms when the powder gets wet in the batter. A second round forms as the batter heats in the oven. That two-step timing makes it more forgiving: a batter can sit for a few minutes before baking without losing all its lift.
Why do some recipes use both?
A recipe may have some acid, but not enough to react with all the soda it would need for a full rise. In that case, King Arthur Baking explains, baking powder does most of the leavening, and the smaller amount of soda is there mainly to neutralize the acid so the bake doesn't taste sour or astringent, adding a little lift along the way. Using both lets a baker balance rise and tang.
Can you use baking powder instead of baking soda?
Yes. To substitute baking powder for baking soda, use three times as much: 3 teaspoons (1 tablespoon) of baking powder for each 1 teaspoon of baking soda. King Arthur Baking gives this 3-to-1 ratio. Don't swap them 1:1; an equal amount of powder gives too little lift and leaves the bake dense and flat.
Expect some differences. Powder brings its own acid, so the recipe's acidic ingredients (buttermilk, yogurt) won't be fully neutralized and the result can taste tangier. That much powder can also leave a faint bitter or metallic taste. A tablespoon is easy to measure: it's exactly 3 teaspoons (see teaspoons in a tablespoon).
For a recipe built on buttermilk and soda, Purdue Extension's chart offers a cleaner swap: in place of 1 cup buttermilk with 1/2 tsp baking soda, use 1 cup regular milk plus 2 tsp more baking powder. More options are on our baking soda substitutes page.
Can you use baking soda instead of baking powder?
Only if you add an acid. Baking soda on its own in a recipe with no acid barely reacts, so the bake rises poorly. The standard fix is homemade baking powder:
- Cream of tartar: 1/4 tsp baking soda + 1/2 tsp cream of tartar = 1 tsp baking powder. King Arthur Baking and Iowa State University Extension give this ratio and add 1/4 tsp cornstarch if you want to mix a batch ahead to store.
- Buttermilk or yogurt: 1/4 tsp baking soda + 1/2 cup buttermilk, sour milk or yogurt = 1 tsp baking powder. Cut the recipe's other liquid by 1/2 cup.
- Vinegar or lemon juice: 1/4 tsp baking soda + 1/2 tbsp vinegar or lemon juice, plus regular milk to make 1/2 cup = 1 tsp baking powder. Reduce other liquid by 1/2 cup. This is the baking soda and vinegar substitute for baking powder that Utah State and Purdue Extension list.
Extension charts differ slightly: some list 5/8 tsp cream of tartar, and some 1/3 tsp soda. Either works. Whichever you use, remember the mix is single-acting. It starts reacting as soon as it gets wet, so get the batter into the oven quickly. Our baking powder substitutes page has the full list.
| If the recipe needs | Use instead | Notes |
|---|---|---|
| 1 tsp baking soda | 3 tsp (1 tbsp) baking powder | May taste slightly bitter; less tang is neutralized |
| 1 tsp baking powder | 1/4 tsp baking soda + 1/2 tsp cream of tartar | Mix right before using; bake promptly |
| 1 tsp baking powder | 1/4 tsp baking soda + 1/2 cup buttermilk or yogurt | Reduce other liquid by 1/2 cup |
| 1 tsp baking powder | 1/4 tsp baking soda + 1/2 tbsp vinegar + milk to make 1/2 cup | Reduce other liquid by 1/2 cup |
What about pancakes?
Pancakes follow the same rules. If a pancake recipe calls for baking powder and you only have soda, use 1/4 tsp soda for each 1 tsp powder along with an acid: cream of tartar, or buttermilk in place of some of the milk. If it calls for soda and buttermilk and you only have powder, use 3 tsp powder per 1 tsp soda. Pancake batter made with a homemade soda-and-acid mix should be cooked right away rather than rested.
How to test baking soda and baking powder for freshness
Neither one spoils in a food-safety sense, but both lose strength over time. Old leavener means flat cakes and dense muffins. Iowa State University Extension recommends two quick tests:
- Baking powder: stir 1 teaspoon into 1/3 cup hot water. If it bubbles, it's still good to use. If not, replace it.
- Baking soda: stir 1 teaspoon into 3 tablespoons vinegar. Bubbling means it's still potent enough for baking.
How long do baking soda and baking powder last?
Iowa State University Extension says opened baking powder should be good for about 6 months for best quality, and gives baking soda about 6 months for best quality as well. Past that, they won't make you sick, but they may not rise as expected, so run the test above before you bake. Check the date on the package too. Baking soda that fails the test still works for cleaning, so there's no need to throw it out.
How to measure leaveners accurately
Leaveners are used in small amounts, so small errors matter. Use measuring spoons, not tableware, and level each spoonful with a straight edge. A gram scale is handy for larger batches, but most US recipes give leaveners in teaspoons. Our conversion hub covers spoon and cup equivalents, and our guide to how to measure flour covers the other common reason bakes come out dense.
Questions people ask
Can I substitute baking powder for baking soda?
Yes. Use 3 teaspoons (1 tablespoon) of baking powder for every 1 teaspoon of baking soda. The result may taste slightly bitter or tangier.
How much baking powder do I substitute for baking soda?
Three times as much. For 1/2 teaspoon baking soda, use 1 1/2 teaspoons baking powder.
Can you use baking soda for baking powder?
Only with an acid. Mix 1/4 teaspoon baking soda with 1/2 teaspoon cream of tartar for each 1 teaspoon of baking powder, then bake promptly.
Can I use baking soda and vinegar as a substitute for baking powder?
Yes. For 1 teaspoon baking powder, use 1/4 teaspoon baking soda plus 1/2 tablespoon vinegar, topped up with milk to 1/2 cup, and cut the recipe's other liquid by 1/2 cup.
Is homemade baking powder double-acting?
No. A baking soda and cream of tartar mix reacts as soon as it's wet, so get the batter into the oven quickly.
Can you make baking powder from baking soda?
Yes. Combine 1/4 teaspoon baking soda and 1/2 teaspoon cream of tartar for each teaspoon you need; add 1/4 teaspoon cornstarch if you're mixing it ahead to store.
Sources
- King Arthur Baking: The difference between baking soda and baking powder, plus substitutions
- Iowa State University Extension AnswerLine: Substitutions for common foods
- Iowa State University Extension AnswerLine: Holiday baking ingredients
- Purdue Extension: Substitutions and equivalents in food ingredients (CFS-145-W)
- Utah State University Extension: Ingredient substitution (FN 255)
- Nebraska Extension: Ingredient substitutions
