Why Substitute Fats in Baking?
Butter and oil perform different roles in dough and batter. Butter contains water (roughly 15–18%) and milk solids, which create flavour, help dough rise through lamination, and contribute to browning. Oil is pure fat with no water content, making it ideal for dense, moist crumbs and for those following plant-based diets.
Fat substitution also depends on health goals. Some recipes favour unsaturated fats from oils for cardiovascular reasons, while others exploit butter's emulsifying properties. Each choice—vegetable oil, coconut oil, or clarified butter—shifts texture, taste, and cooking behaviour.
The mismatch arises because butter weighs more per volume than oils. A cup of butter (240 ml) outweighs a cup of liquid oil because butter's water content adds mass without adding volume in the same way fat does. Coconut oil sits between the two, denser than liquid oils but less dense than butter.
Oil and Butter Conversion Formulas
These ratios convert between standard cooking fats in recipes. The key difference is whether you measure by mass (grams) or volume (millilitres).
Oil (ml) = 0.75 × Butter (ml)
Coconut Oil (grams) = 0.8 × Butter (grams)
Coconut Oil (ml) = 0.75 × Butter (ml)
Oil— Liquid cooking oil (vegetable, canola, or sunflower)Butter— Solid butter or margarine at room temperatureCoconut Oil— Liquid or solid coconut oil (mass and volume have different ratios due to density differences)
Practical Conversion Examples
Example 1: Converting 250 g of butter to liquid oil
Multiply 250 g by 0.75: 250 × 0.75 = 187.5 g of liquid cooking oil.
Example 2: Converting 1 stick of butter to millilitres of oil
One stick equals 125 ml. Multiply by 0.75: 125 × 0.75 = 93.75 ml (or 6 tablespoons) of liquid cooking oil.
Example 3: Converting 1/2 cup of oil back to butter
Half a cup of oil is 120 ml. Divide by 0.75 (or multiply by 4/3): 120 ÷ 0.75 = 160 ml of butter (roughly 2/3 cup).
Coconut oil conversions differ slightly. If a recipe calls for 250 g butter, use 200 g of coconut oil (250 × 0.8). The water content in butter accounts for this discrepancy.
Common Pitfalls When Substituting Fats
Fat substitution in baking carries hidden risks; avoid these frequent mistakes.
- Forgetting that coconut oil has different mass and volume ratios — Coconut oil uses 0.8× for grams but 0.75× for millilitres. Confusing these will leave you with too much or too little fat. Always note whether your recipe specifies weight or volume before converting.
- Ignoring smoke point temperature limits — Oils with unstable fatty acids (like linseed or flaxseed) smoke at low temperatures and ruin dishes. Clarified butter suits high-heat frying better than whole butter, which scorches. Match your fat choice to the cooking temperature required.
- Not accounting for flavour and texture changes — Oil produces softer, moister crumbs; butter creates flakier layers and richer taste. A 1:1 swap won't yield identical results. Cookies spread differently, cakes may sink slightly, and pastries lose lamination if you simply replace one with the other by ratio alone.
- Overlooking coconut oil's saturated fat profile — Despite marketing claims, coconut oil contains roughly twice the saturated fatty acids of butter per serving. If you're substituting for health reasons, coconut oil isn't a meaningful improvement; unsaturated oils like canola or olive oil are better choices.
Butter or Oil: Which Should You Use?
Neither is universally superior—context matters. Butter excels in pastries, cakes, and cookies where flavour and structure shine. The milk solids brown during baking, adding depth, and the water content helps dough rise. Oil works best in brownies, banana bread, or quick breads where you want density and moisture without distinct buttery notes.
For frying, oil is safer because it tolerates higher temperatures without degrading. Use clarified butter (ghee) if you want a buttery flavour at high heat. Whole butter will splatter and burn. For health-conscious cooking, unsaturated oils from seeds, nuts, or olives provide better cardiovascular benefits than saturated fats in coconut oil or butter.
Vegan baking demands oil or plant-based butter substitutes. Applesauce or mashed bananas add moisture but change crumb structure significantly. Proper fat ratios matter most when precision is critical—bread baking, macarons, laminated doughs, and custard-based items all suffer from careless substitutions.