Baking Substitution Guide

Yes — but use 1/4 the amount. 1 tsp baking powder = ¼ tsp baking soda + ½ tsp cream of tartar (to add the acid baking soda needs). Without cream of tartar, you also need an acidic ingredient (buttermilk, lemon juice, yogurt) in the recipe, otherwise the soda won't activate.

For binding: 1 egg = 1 tbsp ground flaxseed + 3 tbsp water (let sit 5 min). For leavening: 1 egg = ¼ cup whipped aquafaba (chickpea liquid). For moisture: 1 egg = ¼ cup unsweetened applesauce or mashed banana. The best substitute depends on the egg's role in the recipe.

Yes — use ¾ the amount. 1 cup butter = ¾ cup neutral oil. Butter has ~20% water; oil is 100% fat, so slightly less is needed. Cakes made with oil are often more moist since oil stays liquid at room temperature. Texture may be slightly denser and flavor will be more neutral.

Add 1 tbsp lemon juice or white vinegar to 1 cup milk, stir, and let sit for 5–10 minutes until it curdles slightly. Or use 1 cup plain yogurt thinned with ¼ cup milk. Sour cream + milk also works. The key is having an acidic dairy that reacts with baking soda.