Butter to Oil Conversion
The conversion ratios and chemical adjustments required when swapping solid butter for liquid oil or shortening in baking.
1 Cup Butter = 3/4 Cup Oil + 2 Tbsp liquid • 1 Stick Butter = 6 Tbsp Oil + 1 Tbsp liquid
Butter is an emulsion containing about 80% fat, 16-18% water, and 2-4% milk solids. Vegetable oil is 100% pure fat. Because of this water difference, you cannot substitute oil for butter at a 1:1 ratio. Replacing butter with the same amount of oil will make your bakes greasy and flat, as the missing water prevents steam from rising to create structure. To substitute oil for butter: use 3/4 the amount of oil (e.g. 3/4 cup oil for 1 cup butter) and add 2 tablespoons of water or milk to replace the lost moisture.
Vegetable shortening (like Crisco) is also 100% pure fat, but it remains solid at room temperature. When substituting shortening for butter, use a 1:1 ratio by weight, but add 2 tablespoons of liquid per cup of shortening to compensate for the lack of water in the fat. Shortening has a higher melting point than butter, which prevents cookies from spreading too quickly, resulting in taller, thicker, and softer bakes with a less pronounced buttery flavor.
Substituting oil in cookie recipes that rely on creaming butter and sugar. Oil cannot trap air bubbles like solid butter, resulting in thin, dense, spreading cookies.
Neutral oils like canola, safflower, or vegetable oil are preferred in baking because they do not add flavor. Extra virgin olive oil adds fruitiness, best for specialty olive oil cakes.
Swapping butter for oil is great in muffins, quick breads, and carrot cakes where moisture and longevity are preferred over structure and lift.
Replace 1 cup butter with 3/4 cup neutral oil + 2 tbsp milk or water. Replace 1 cup butter with 1 cup solid shortening + 2 tbsp liquid.