Baking powder makes flour rise by producing carbon dioxide gas bubbles throughout the batter or dough. Those tiny bubbles expand during mixing and again in the oven, pushing the mixture upward and creating the soft, airy texture you expect in cakes, muffins, biscuits, and quick breads. Without it, most non-yeast baked goods would come out dense and flat.
How Baking Powder Creates Lift
Baking powder is a pre-mixed combination of baking soda (sodium bicarbonate) and one or more powdered acids. When you stir baking powder into flour and then add wet ingredients, the baking soda reacts with the first acid to release carbon dioxide gas. This is the initial rise, and it starts as soon as the batter gets wet.
The second rise happens in the oven. A second powdered acid in the mixture stays dormant until the temperature climbs above roughly 170°F, at which point it reacts with the remaining baking soda and releases another wave of gas bubbles. This two-stage reaction is why most baking powder sold today is labeled “double-acting.” It gives you a window of time between mixing and baking without losing all your lift.
What Happens Inside the Batter
Carbon dioxide alone isn’t enough. The gas needs something to trap it, and that’s where the flour comes in. When flour mixes with liquid, its proteins form a stretchy network (gluten in wheat flour, or starch gels in gluten-free flours) that acts like thousands of tiny balloons. Each carbon dioxide bubble gets caught inside this network. As the bubbles expand from oven heat, they stretch the surrounding structure, and the batter rises.
Once the temperature gets high enough, the proteins and starches set permanently, locking the expanded bubbles in place. That’s what gives a muffin or cake its spongy crumb. If the gluten network is too weak or the batter is overmixed and tough, the bubbles either escape before the structure sets or can’t expand properly, and you end up with uneven texture.
How Much Baking Powder to Use
The standard ratio is about 1 to 1.5 teaspoons of baking powder per cup (120 grams) of all-purpose flour. A common rule of thumb in professional baking is 1 gram of baking powder for every 25 grams of flour, which works out to roughly 40 grams of baking powder per kilogram of flour.
Self-rising flour, which has the leavening already built in, follows the same math. King Arthur Baking’s recipe for homemade self-rising flour calls for 1½ teaspoons of baking powder and ¼ teaspoon of salt per cup of all-purpose flour. If your recipe calls for self-rising flour and you only have regular flour, that’s the conversion.
Too Much or Too Little Changes Everything
More baking powder doesn’t mean more rise. Use too much and the batter over-inflates, then collapses as the structure can’t support all those bubbles. The result is a sunken, coarse crumb. Excess baking soda that doesn’t get neutralized by the acids also leaves a bitter, soapy taste.
Too little baking powder gives you the opposite problem: not enough gas to lift the batter, so you get a dense, heavy product. If your cakes or muffins consistently come out flat despite following the recipe, the baking powder itself may be the culprit. It loses potency over time, especially if moisture gets into the container. You can test it by stirring half a teaspoon into a cup of hot water. Fresh baking powder will fizz vigorously right away. If you get weak or no bubbles, it’s time to replace it.
Baking Powder vs. Baking Soda With Flour
Baking soda is just one ingredient: sodium bicarbonate. It needs an acid already present in the recipe (buttermilk, yogurt, lemon juice, brown sugar, cocoa powder) to produce carbon dioxide. Baking powder brings its own acids along, so it works in recipes that don’t contain an acidic ingredient.
This is why pancake recipes using regular milk call for baking powder, while recipes using buttermilk often call for baking soda, or a combination of both. The choice isn’t arbitrary. It’s about making sure there’s a matching acid for every bit of baking soda so you get full gas production and no leftover alkaline flavor.
Effects Beyond Rising
Baking powder also influences browning and tenderness. The sodium bicarbonate in it raises the pH of the batter slightly toward the alkaline side, which accelerates browning reactions on the surface. That’s why biscuits made with baking powder develop a golden crust more easily than an unleavened dough would.
The gas bubbles themselves affect tenderness. By expanding the structure and creating air pockets, baking powder physically interrupts the gluten network, making the final product more delicate. This is part of why cake flour recipes with baking powder yield a tender crumb, while bread doughs relying on yeast develop a chewier, denser texture from longer gluten development.
The acids in baking powder play a role too. In commercial baking powder, roughly 58% of the mixture is the acid component, with the remaining 42% being baking soda. These acids help balance the pH so the finished product doesn’t taste metallic or soapy, and they control the timing of gas release so most of the lift happens when it’s useful, not while the batter is sitting on the counter.