Swapping Olive Oil for Butter in a Cake

An olive oil cake stays moist for days where a butter cake dries out overnight, and it carries a subtle savoury depth butter cannot. But you cannot just pour oil in where butter went — the swap has a ratio, and a couple of rules that decide whether it works.

Butter and olive oil are not interchangeable spoon for spoon, because butter is only about 80% fat — the rest is water and milk solids — while olive oil is pure fat. Match them by weight of butter and you overshoot the fat and drown the crumb. The fix is a simple ratio: use three parts oil for every four parts butter. In everyday terms, three-quarters of a cup of oil for each cup of butter a recipe calls for. Because you have also removed butter’s water, drop the other liquids by a tablespoon or two to keep the batter right.

Why oil often makes the better cake

Butter is prized for creaming — whipping air into sugar for a light, fine crumb — so it shines in delicate sponges and shortbread. But for many cakes, oil wins. It stays liquid at room temperature, so the crumb never firms up and dries the way a butter cake does; olive oil cakes are famous for staying moist and tender for days. Oil also carries flavour differently, giving a moist, almost custardy density that suits citrus, almond, yoghurt and chocolate cakes beautifully.

The trap: using a fierce, peppery oil

Here is where people go wrong. They reach for their most characterful, bitter, peppery extra virgin — and the finished cake tastes faintly of pepper and green bitterness, which fights the sugar. For baking you want a mild, ripe, buttery oil: a gentle Arbequina-style extra virgin, or a soft blend low in bitterness. Save the grassy, throat-catching stuff for salads. A good baking oil should whisper fruit into the cake, not shout pepper over it.

Two more small rules

Oil-based batters tend to bake a touch faster, so start checking five to ten minutes before the recipe’s time. And because there is no solid butter to cream, you simply whisk the oil into the sugar and eggs — no waiting for butter to soften, no risk of over-creaming. That makes olive oil cakes some of the easiest of all to throw together: one bowl, a whisk, and a mild bottle of oil.

Butter	Olive oil
Use as the recipe states	Use ¾ the amount (3:4 by volume)
~80% fat, rest water and solids	100% fat — cut other liquid slightly
Cream with sugar for a light crumb	Just whisk into sugar and eggs
Firms and dries within a day	Stays moist and tender for days
Any butter is fine	Use a mild, buttery oil — never a peppery one

The ratio	3 parts oil to 4 parts butter
Easy version	¾ cup oil per 1 cup butter
Adjust liquid	Reduce other liquids by 1–2 tbsp
Best oil	Mild, ripe, buttery extra virgin (e.g. Arbequina)
Avoid	Bitter, peppery, robust oils
Baking time	Check 5–10 minutes early

Making the swap

• Use ¾ cup of oil for every cup of butter, and cut other liquids by a spoon or two.
• Choose a mild, buttery oil — never a fierce, peppery one.
• Just whisk oil into the sugar and eggs; no creaming needed.
• Start checking early; oil batters bake a little faster.

Olive oil for butter in cake: common questions

How much olive oil replaces butter in a cake?

Use three parts oil to four parts butter — about three-quarters of a cup of oil for each cup of butter. Butter is only ~80% fat, so a straight swap would use too much.

Do I need to change anything else?

Yes. Reduce the recipe’s other liquids by a tablespoon or two, since you have removed the water in butter, and start checking for doneness a little early.

Which olive oil is best for baking?

A mild, ripe, buttery one such as an Arbequina-style extra virgin. Avoid bitter, peppery oils, which leave a green, savoury taste that fights the sugar.

Will an olive oil cake taste of olives?

With a mild oil, only faintly and pleasantly — a gentle richness rather than an olive flavour. A robust oil, though, really will taste peppery.

Is an oil cake better than a butter cake?

For moistness and keeping, usually yes — oil cakes stay tender for days. Butter still wins where you need a light, creamed crumb, as in a fine sponge.

Drawn from standard butter-to-oil baking conversions and the behaviour of oil versus butter in a crumb.