You can use olive oil instead of butter at a ratio of 3/4 cup of olive oil for every 1 cup of butter. That is the whole rule in one sentence, and it works because butter is only about 80 percent fat — the rest is water and milk solids — while olive oil is 100 percent fat. Using the same volume of oil as butter would add too much fat to the recipe, so you use three quarters as much. The swap works well in cakes, muffins, quick breads, focaccia and roasted vegetables, where the oil keeps the crumb moist for longer than butter does. It does not work in recipes that rely on creaming butter with sugar, laminated pastry, or shortbread — and that distinction is the difference between a successful swap and a ruined batch.

Olive oil in baking surprises people who have only ever used it for salad dressing. In a chocolate cake, a good extra virgin olive oil adds a fruity, peppery depth that butter cannot match. In a lemon drizzle cake, it keeps the crumb tender for days. In focaccia, it is not a substitute at all — it is the traditional fat, and butter would be the odd choice. The key is to choose the right oil: a mild, late-harvest extra virgin oil for delicate cakes, a robust early-harvest oil only where its flavour is welcome, and a refined or light olive oil for anything where you want the fat without the flavour. All of them weigh the same — one cup of olive oil is 216 grams — so the ratio does not change with the grade.

The ratio, in a table

The table below converts butter to olive oil for the amounts you are most likely to meet. The rule is always the same: multiply the butter by three quarters. For small amounts, the tablespoon figures are the useful ones — 1 tablespoon of butter (14 grams) becomes about 2 1/4 teaspoons of oil, which most bakers round to 2 teaspoons.

Butter called for Olive oil to use Notes
1 tablespoon 2 1/4 teaspoons Round to 2 teaspoons
2 tablespoons 1 1/2 tablespoons
1/4 cup 3 tablespoons 45 ml
1/3 cup 1/4 cup 60 ml
1/2 cup 6 tablespoons 90 ml
2/3 cup 1/2 cup 120 ml
3/4 cup 9 tablespoons 135 ml
1 cup 3/4 cup 180 ml
1 1/2 cups 1 1/8 cups 270 ml
2 cups 1 1/2 cups 360 ml

By weight, the conversion is also simple: one cup of butter weighs 227 grams, and three quarters of a cup of olive oil weighs about 162 grams. If you are weighing ingredients, that is the number to use. Note that you are not just swapping the fat — you are also removing the water that butter contains (about 34 grams per cup) and the milk solids. In most cakes and muffins that water loss does not matter, but in a recipe where the butter's water contributes to steam and lift, such as a rough puff pastry, it does — which is one more reason the swap is limited to the recipes below.

Worked examples

Example 1: An olive oil chocolate cake that stays moist for days

A chocolate cake recipe calls for 1/2 cup of butter — 113 grams. You replace it with 6 tablespoons of olive oil (90 ml). Use a mild extra virgin oil, and whisk it with the sugar and eggs exactly as you would have creamed the butter. The cake will have a slightly denser, fudgier crumb than the butter version, and it will stay moist for three or four days instead of drying out after one — oil does not solidify at room temperature the way butter does, so the crumb stays soft. The olive oil flavour disappears behind the cocoa, so nobody will guess the swap. This is the best first recipe to try the substitution in, because chocolate forgives everything.

Example 2: Focaccia, where olive oil is the original

A focaccia recipe calls for 1/4 cup of butter in the dough — an unusual choice, since traditional focaccia uses olive oil throughout. Replace it with 3 tablespoons of olive oil, and use more oil to grease the pan and drizzle over the top before baking. Here the swap is not a compromise but an improvement: the olive oil gives the focaccia its characteristic golden, crisp base and its fruity aroma, and the bread will keep better. This is the recipe where the substitution stops being a substitution and becomes the right ingredient.

Example 3: A lemon drizzle cake for a dairy-free guest

A lemon drizzle cake calls for 1 cup of butter, and you need a dairy-free version for a guest. Replace it with 3/4 cup of mild olive oil (180 ml). Whisk the oil with the sugar until pale — it will not trap air the way creamed butter does, so the cake will be a little denser, but the lemon zest and the drizzle will carry the flavour. Bake it in the same tin at the same temperature, but check it five minutes early, because oil-based cakes sometimes bake slightly faster. The result is a moist, fragrant cake that no one will identify as dairy-free unless you tell them.

What changes in the result

Three things change when you swap olive oil for butter. First, the flavour: olive oil adds a fruity, sometimes peppery note. In chocolate cake, citrus cake and herb breads, that note is welcome; in a vanilla sponge or a sugar cookie, it can taste out of place, which is why a mild or refined oil is better there. Second, the texture: oil-based cakes are moister and stay soft longer, but they are also denser, because oil cannot trap air the way creamed butter does. A cake made with oil will never be as light and fluffy as a cake made with properly creamed butter. Third, the browning: butter's milk solids brown and add flavour, while olive oil does not brown the same way, so oil-based cakes can look paler. If the top of your cake is pale, give it a few extra minutes or brush it with a little milk or syrup before baking.

The practical consequence is that the swap is best in recipes where the fat is melted or liquid anyway — muffins, quick breads, traybakes, focaccia, roasted vegetables — and worst in recipes where the fat's solid state matters. Creaming is the clearest example: beating butter with sugar traps thousands of tiny air bubbles that expand in the oven and lift the cake. Oil cannot do this. A Victoria sponge made with oil will be flat and dense. Pastry is the other example: butter's solid fat creates layers and flakiness; oil makes a crumbly, short pastry that is pleasant in its own way but is not puff pastry or shortcrust.

When not to substitute

Do not use olive oil instead of butter in recipes that rely on creaming butter with sugar (sponge cakes, most layer cakes, many cookies), in laminated pastry (croissants, puff pastry, Danish), or in shortbread, where butter is the dominant flavour and the entire structure. Do not use it in buttercream or frosting — oil will not whip, will not hold its shape, and will taste greasy. Do not use a strongly flavoured extra virgin oil in a delicate vanilla or white cake; use a mild or refined olive oil instead. And do not use olive oil in a recipe where the butter is browned for flavour — brown butter's nutty taste has no equivalent in oil, and the recipe will lose its defining note.

One more caution: olive oil has a lower smoke point than refined vegetable oil — about 190 to 210°C for extra virgin, higher for refined. For baking, that does not matter, because the oven temperature is below the smoke point and the oil is protected by the batter. For frying, it matters more: do not use extra virgin olive oil for high-heat frying, where it will smoke and taste bitter.

Frequently asked questions

How much olive oil do I use instead of 1 cup of butter?

Use 3/4 cup of olive oil for 1 cup of butter. That is 180 ml, or about 162 grams by weight. The reason is that butter is about 80 percent fat and 20 percent water and milk solids, while olive oil is 100 percent fat, so you need less oil to get the same amount of fat.

Can I use olive oil instead of butter in cookies?

Sometimes. In soft, chewy cookies like chocolate chip cookies, the swap works — the cookies will be a little flatter and chewier, and will stay soft longer. In cookies that rely on creamed butter for lift and structure, such as shortbread or a light sugar cookie, the swap fails: the cookies will spread too much and taste oily. For cookies, use a mild olive oil and expect a denser result.

Does olive oil make cakes taste like olives?

Not if you choose the right oil. A mild, late-harvest extra virgin oil or a refined olive oil has almost no olive flavour in a baked cake, especially in a chocolate or citrus cake. A robust, peppery early-harvest oil will leave a noticeable fruity note, which is welcome in a Mediterranean-style cake and unwelcome in a vanilla sponge. When in doubt, taste the oil first — if it is bitter or peppery on its own, it will be noticeable in the cake.

Is olive oil healthier than butter?

Olive oil is mostly monounsaturated fat, while butter is mostly saturated fat, so olive oil is generally considered the healthier choice. It also contains polyphenols and vitamin E. That said, both are calorie-dense fats — about 120 calories per tablespoon for olive oil and about 100 for butter — so the health difference is about the type of fat, not the amount. The swap is a reasonable health choice, but it is not a low-calorie choice.

Can I use olive oil instead of butter in pastry?

You can make a short, crumbly pastry with olive oil — it is the traditional fat in some Mediterranean pastries — but you cannot make puff pastry, croissants or a flaky shortcrust with oil. Those rely on solid butter creating layers that separate in the oven. An oil pastry will be tender and crumbly rather than flaky, which is fine for a rustic tart but not for a pie that needs to hold its shape.

What type of olive oil is best for baking?

A mild extra virgin olive oil is best for cakes where you want a hint of fruitiness, and a refined or light olive oil is best where you want no olive flavour at all. Avoid robust, peppery, early-harvest oils in delicate baking. For focaccia and savoury breads, a good extra virgin oil is the right choice — its flavour is part of the dish.

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