Baking soda and baking powder look similar and get used interchangeably by accident more often than any other pantry mix-up. They aren’t the same thing, they aren’t always swappable, and mixing them up is one of the most common reasons a copycat baking recipe comes out flat, metallic-tasting, or over-risen and collapsed.
Baking Soda
Pure sodium bicarbonate — a base that needs an acid (buttermilk, brown sugar, lemon juice, cocoa powder, vinegar) to react with. That reaction produces carbon dioxide gas, which is what creates lift. Because the reaction starts as soon as the wet and dry ingredients meet, recipes using baking soda are usually baked promptly after mixing, before the gas escapes. It’s roughly three to four times stronger than baking powder by volume, which is why recipes call for such small amounts.
Baking Powder
Baking soda pre-mixed with a powdered acid (usually cream of tartar or a similar compound) and a moisture-absorbing filler like cornstarch, so it doesn’t need an additional acid ingredient in the recipe to work. Most baking powder sold today is “double-acting,” meaning it releases gas twice: once when it gets wet, and again when it hits oven heat, which gives more forgiving timing than baking soda.
Why You Can’t Always Swap One for the Other
Baking soda needs an acid present to activate — use it in a recipe with no acidic ingredient and it won’t react properly, leaving a flat result with a metallic, soapy aftertaste from the unreacted sodium bicarbonate. Baking powder already contains its own acid, so it works without one, but it’s much weaker per teaspoon, so a straight swap in either direction throws off both the rise and the flavor balance.
Why Recipes Sometimes Use Both
A recipe with an acidic ingredient (like buttermilk or brown sugar) might still call for baking powder in addition to baking soda: the soda neutralizes the acid’s flavor and provides some initial lift, while the baking powder supplies additional, more reliable lift that doesn’t depend on how much acid is actually present. This is common in recipes where the acid’s amount is more about flavor than being precisely calibrated for leavening.
Substituting Between the Two
- Baking powder for baking soda: use about 3× the amount of baking powder, but be aware the result may taste slightly different since baking powder’s acid changes flavor differently than whatever acid the recipe originally paired with soda
- Baking soda for baking powder: use ⅓ the amount of baking soda, and add an acid (like ¼ to ½ teaspoon cream of tartar per ¼ teaspoon soda, or swap some liquid for buttermilk/yogurt) or the soda won’t activate properly
Buying Guide
Keep both on hand — they aren’t interchangeable enough to rely on just one, and a surprising number of recipes on this site use both together. Replace baking powder roughly every 6 months to a year, since its double-acting reaction weakens with age even before the box’s expiration date; baking soda keeps longer but loses potency too. A quick freshness test for either: baking soda fizzes vigorously in vinegar, baking powder fizzes in hot water — if it barely reacts, it’s time to replace it.
Recipes on CopyKitchen That Use Baking Soda or Baking Powder
- Make Panera Cinnamon Crunch Bagel at Home for Less
- Make Starbucks Lemon Loaf at Home for Less
- Pumpkin Bread Just Like Starbucks’s
- The Best Copycat Auntie Anne’s Soft Pretzels Recipe
- Homemade Cracker Barrel Pancakes
- How to Make Red Lobster Cheddar Bay Biscuits at Home
Frequently Asked Questions
Why does my baked good taste metallic or soapy?
Too much baking soda relative to the acid available to neutralize it is the most common cause — the unreacted sodium bicarbonate leaves that distinct metallic, slightly bitter aftertaste.
Why did my recipe not rise even though I used baking soda?
Baking soda needs an acidic ingredient to react and produce lift. If the recipe doesn’t have one (or you substituted out the acidic ingredient it was paired with), the soda won’t activate properly.
How do I know if my baking powder is still good?
Drop a teaspoon into a small cup of hot water. If it fizzes vigorously right away, it’s still active. A weak or absent reaction means it’s time to replace it.
