Every rise in baking traces back to the same physics: gas released inside a dough or batter stretches it into the light, open crumb we want to eat. The practical question for any baker is which of the three common leaveners—yeast, baking soda, or baking powder—belongs in a given recipe. The answer comes down to two checks: what acidic ingredients your recipe contains, and how much rise time and texture you want. Yeast is a living organism that needs time and sugar; baking soda is a chemical that reacts the moment it meets acid and moisture; baking powder carries its own acid and only needs liquid and heat.

The Science of Leavening: How Baked Goods Rise

A leavening agent is, in the simplest terms, a substance that causes dough to expand by releasing gas once it is mixed with liquid, acid, or heat, as KitchenAid's baking reference explains. That trapped gas is what gives baked goods their volume, texture, and crumb. The gases and the fermentation process leaveners produce lighten batter and dough, and as a home economics curriculum from CAERT notes, even a small change in the amount of a leavening agent can noticeably affect the quality of the finished product.

Not all leaveners work the same way. The CAERT curriculum groups them into chemical, organic, mechanical, and natural categories; of the three covered here, baking soda and baking powder are chemical leaveners—human-made substances that react with other chemicals to release carbon dioxide—while yeast is an organic one. Sally McKenney, who writes the baking blog Sally's Baking Addiction, puts the shared principle plainly: both white powders are made from sodium bicarbonate, which, when combined with an acid, produces carbon dioxide, and that gas is what lifts baked goods in the oven. Air and steam can also leaven, but this guide concentrates on the three pantry staples.