Kitchen converters
Oil to Butter Substitution
Use about 80% of the butter weight in oil, or about 3/4 of the butter volume. Texture and browning will still change.
Reviewed September 2026
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Butter is not all fat. Oil is.
USDA FoodData Central entries for stick butter show a large water fraction plus milk solids. Typical unsalted butter is roughly four-fifths fat by weight and the rest is water and protein. Liquid vegetable oil is essentially all fat. If you pour oil equal to the butter weight, the batter gets more fat and less water than the recipe designed.
Home bakers therefore use about 80 percent of the butter weight in oil, which is also about three-quarters of the butter volume. This page does that arithmetic and stops. It does not promise identical cookies.
Parents reach for the swap when a birthday guest cannot have dairy, when the last stick is gone, or when a muffin tin needs to be dairy-light for a classroom. Flavor and browning still change because butter brown bits and milk sugars are missing.
How to use the oil substitution
Enter the butter grams the recipe lists. If the recipe lists sticks, convert first: one US stick is 113 g. If it lists cups, one cup of butter is 227 g on this site.
Read oil grams. Then read oil cups using 218 g of oil per cup. Pour that oil. Do not add the water back unless you are following a tested dairy-free formula that already accounts for it.
Formula and a 1 cup butter example
Oil grams = butter grams × 0.8. Oil cups = oil grams ÷ 218.
A recipe that calls for 227 g of butter (1 cup) becomes 227 × 0.8 = 181.6 g of oil. Cups of oil = 181.6 ÷ 218 = 0.83 cup. That sits next to the familiar "use 3/4 cup oil for 1 cup butter" note. Three-quarters of a cup is 0.75 cup, a little less than 0.83. Many cards round down to 3/4 for easier measuring. This calculator keeps the 80 percent weight rule and shows the exact cup fraction.
One stick (113 g) becomes 90.4 g of oil, or 90.4 ÷ 218 = 0.41 cup, a scant 7 tablespoons.
Butter weight to oil at 80 percent and 218 g oil per cup
| Butter in the recipe | Oil grams | Oil cups |
|---|---|---|
| 113 g (1 stick) | 90.4 | 0.41 |
| 227 g (1 cup) | 181.6 | 0.83 |
| 56.8 g (4 tbsp) | 45.4 | 0.21 |
| 454 g (1 lb) | 363.2 | 1.67 |
What to type when the recipe is in sticks or cups
Convert sticks and cups to grams before this box, or use the butter-weight converter and paste the gram result here. Do not enter 1 to mean 1 stick. The field is grams.
If the recipe already lists oil, you do not need this page. If the recipe lists shortening, this 80 percent rule is the wrong tool. Shortening is a different fat system.
Melted butter poured into a cup is still butter, water included. Do not run melted butter through this page as if it were oil. You would cut the fat and still have the water in a confusing way. Use the butter-weight converter for melted butter, then come back only if you still want oil.
What changes in the bake
Oil stays liquid at room temperature. Cookies often spread more. Cakes can taste moister on day one and a bit greasier on day two. Creased muffin papers show oil spots more than butter spots.
Chill cookie dough 30 minutes if the first tray spreads into one sheet. For a layer cake that must stand on a classroom desk, keep some structure: a blend of oil and a dairy-free solid fat is more reliable than a full oil swap in a high-ratio butter cake.
How to read 80 percent and 3/4 volume together
If your oil cup result is 0.83 and you only have a 1/4-cup measure, use three 1/4 cups plus 1 tablespoon (about 0.81 cup) and stop. Do not "round up to a full cup." That extra 0.17 cup is about 37 g of oil, which is another 1.3 ounces of fat in a single batch.
Dietary Guidelines treat oils as part of a healthy pattern and ask people age 2 and older to keep saturated fat under 10 percent of calories. Butter is high in saturated fat. A canola or soybean oil swap lowers saturated fat. It does not lower added sugar in a frosted cupcake.
Classroom cakes and allergy tables
Oil avoids milk fat. It does not avoid wheat, egg, or soy lecithin in a mix. Read the mix box. Cross-contact on a shared spatula still matters for a child with a milk allergy.
When the oil swap is a reasonable first try
| Bake | Oil swap usually works? | Watch for |
|---|---|---|
| Muffins and quick breads | Often | Greasy liner, weaker rise |
| Snack cakes from a mix | Often | Label allergens besides milk |
| Rolled sugar cookies | Sometimes | Spread; chill dough |
| Laminated dough or pie crust | No | Need a solid fat |
| Buttercream frosting | No | Need a solid fat and different method |
Which bottle to pull after the gram number appears
Canola, soybean, and refined sunflower oils are mild in a vanilla cupcake. Extra-virgin olive oil will taste like olive oil. That can be right in an orange-olive-oil cake and wrong in a funfetti school square. The 80 percent math does not change. The flavor does.
Coconut oil is solid in a cool kitchen. Melt it and measure as a liquid, or the cup figure will be a packed solid cup, which is a different density than 218 g. If you substitute melted coconut oil using this page, you still lose butter's water. The crumb may be tender and the coconut flavor will show.
Spray oil on a pan is not the 181 g in the bowl. Parents sometimes "cut butter" by spraying the pan and then still pouring a full cup of oil into the batter. That is two fats. Use the calculated oil in the batter and a thin film on the pan.
A dairy-free frosting still needs a solid fat if you want peaks. Do not try to beat the leftover oil from this swap into powdered sugar and expect buttercream. Make a tested dairy-free icing or serve the cake with berries and a dollop of coconut yogurt. Watch the yogurt label for added sugars.
Leftover oil-based muffins freeze well. Wrap them once they are cool. A warm muffin in a plastic bag sweats, then turns gummy in a lunchbox. Freeze, then move one muffin to the fridge the night before school.
Browned butter recipes are asking for the milk solids to toast. Oil cannot brown that way. If the recipe title is "brown butter," keep butter or use a tested browned-butter substitute, not this 80 percent page.
A banana bread that already uses oil does not need a second conversion. A banana bread that uses 113 g butter and one mashed banana can take the 90 g oil swap and will taste a bit less rich. The banana still supplies water. That is why quick breads forgive the swap more than puff pastry does.
If two adults argue between 3/4 cup and 0.83 cup, pick 0.80 cup (12 tablespoons plus 2 teaspoons) and write it down. Consistency across birthday seasons matters more than winning the 0.03 cup debate.
Limits of an 80 percent kitchen rule
European butter can run a higher fat percentage than US 80-percent-fat sticks. If you already bake with a high-fat imported block, the 0.8 factor can be a little generous. Olive oil flavor will show in a vanilla cupcake. Neutral oil hides better.
This is not a calorie calculator and not a saturated-fat prescription. AHA materials on dietary fat still prefer replacing saturated fat with unsaturated fat in the overall pattern, not adding oil on top of unchanged butter.
Deep-frying leftover birthday cake is not a substitution method. Keep oil below its smoke point. Refrigerate leftover oil-based batter cakes on the same leftover timeline as other perishable bakery: FSIS leftover guidance is 3 to 4 days in the refrigerator once the cake contains eggs and dairy alternatives that still spoil.
Ghee is almost all fat, like oil, but it is solid when cool. Do not treat ghee as this liquid-oil cup result unless you melt and measure. Flavor is nuttier than canola and will show in a pale vanilla crumb.
How it works
Butter is water plus fat. Straight oil is all fat, so bakers typically use less oil than butter by weight.
Frequently asked questions
Will cookies spread more?
Often yes. Oil is liquid at room temperature. Chill dough if spread is a problem.
Related calculators
References
- USDA Agricultural Research Service. FoodData Central
- FDA. Added Sugars on the Nutrition Facts Label
- NIST. SI Units - Volume
- USDA ARS. Measurement conversion tables
- NIST Office of Weights and Measures. Metric Household
- USDA and HHS. Dietary Guidelines for Americans, 2020-2025
- Vos et al., American Heart Association. Added Sugars and Cardiovascular Disease Risk in Children
- USDA FSIS. Leftovers and Food Safety
Kitchen tools are estimates for home cooking. Nutrition tools are screening aids, not a diagnosis. They are not a substitute for a pediatrician or registered dietitian. Food-safety temperatures follow USDA FSIS. Do not reuse leftover meat brine.