Butter to oil converter
Swapping butter for oil isn't a 1:1 trade. Get the exact ratio for cookies, cakes, and bread.
Butter is 20% water
I genuinely believe that subbing oil for butter is one of the easiest ways to ruin a cake if you aren't careful. Butter isn't pure fat; it’s about 80% fat and 20% water and milk solids. Oil is 100% fat. If you swap them 1:1, your cake will be greasy and heavy. The "Golden Ratio" is 3/4 parts oil for every 1 part butter. This accounts for the missing water and keeps the texture moist without being oily.
When NOT to swap: If your recipe asks you to "cream butter and sugar," don't use oil. Creaming creates tiny air pockets that oil just can't hold. If you use oil there, your cake will be flat and dense. Stick to oil for recipes that ask for melted butter or just "fats."