Butter substitutes
The best substitute for butter is block margarine: 1:1, using firm stick or block margarine, never a soft tub spread. Tub spreads carry far more water and will wreck pastry and cookies. Even block margarine browns less and tastes flatter, so a shortbread loses most of its character.
Why it matters. Butter is roughly 80 percent fat, 16 percent water and 4 percent milk solids, and all three matter. The solid fat traps air when creamed, the water turns to steam and creates flake in pastry, and the milk solids brown for flavour. Any swap changes at least one of those.
BestBlock margarine
●●●●○1:1, using firm stick or block margarine, never a soft tub spread
Keeps the fat, texture and tenderizer roles; loses flavour.
Tub spreads carry far more water and will wreck pastry and cookies. Even block margarine browns less and tastes flatter, so a shortbread loses most of its character.
Ghee
●●●●○7/8 cup ghee per 1 cup butter
Keeps the fat, flavour and texture roles; loses tenderizer.
Pure butterfat with the water and milk solids removed, so it is nuttier and does not steam. That missing water means pastry will be noticeably less flaky.
Shortening
●●●○○1 cup shortening + 2 tbsp water per 1 cup butter
Keeps the fat, texture and tenderizer roles; loses flavour.
No flavour, no browning and no water unless you add it, so cookies bake paler and taller and taste plain. It does make exceptionally tender pastry.
Coconut oil
●●●○○1:1, solid where the recipe creams the butter and melted where it melts it
Keeps the fat, texture and tenderizer roles; loses flavour.
Solid coconut oil creams better than you would expect, but it contains no water, so there is no steam and less flake. Virgin coconut oil tastes of coconut; refined does not.
Lard
●●●○○1:1
Keeps the fat, texture and tenderizer roles; loses flavour.
Its large fat crystals make outstandingly flaky pastry, but it tastes faintly savoury and it is not vegetarian.
Neutral oil
●●●○○3/4 cup oil per 1 cup butter, and only where the recipe melts the butter
Keeps the fat, texture and tenderizer roles; loses flavour.
Oil cannot be creamed, so it will not aerate a cake batter or hold air in a cookie dough. You also lose the browning and the flavour. Cakes stay softer when cold.
Full-fat Greek yogurt
●●○○○Replace up to half the butter with an equal weight of Greek yogurt
Keeps the texture and tenderizer roles; loses fat and flavour.
Adds moisture and acid instead of fat. Push past half and the bake goes dense and rubbery, and there is no browning or richness at all.
Other fat substitutes
Measuring by weight instead? Use the kitchen converter.