Thin, tangy cultured milk. Traditionally the liquid left over from churning butter, though what you buy today is milk soured deliberately with bacterial cultures.
What it does in a recipe: Acid, liquid, and tenderiser in one — it reacts with baking soda for lift and keeps crumb soft. Pick the swap that covers that job — the ratios below are written so you can act on them without doing any arithmetic.
Also called: Cultured buttermilk
5substitutes
2close matches
Dairy & milkscategory
Quick answer
Milk + lemon juice or vinegar
1 cup buttermilk = 1 cup milk + 1 tbsp lemon juice or white vinegar
All substitutes, best first
5 ways to replace buttermilk
Milk + lemon juice or vinegar
Closest match
1 cup buttermilk = 1 cup milk + 1 tbsp lemon juice or white vinegar
The acid curdles the milk and drops its pH into buttermilk's range, so it still reacts with baking soda for lift and still tenderises gluten for a soft crumb.
MethodStir the acid into the milk and let it stand 5-10 minutes until it thickens slightly and looks curdled before using. Skipping the rest is the most common reason this swap underperforms.
Trade-offThinner than real buttermilk and without its cultured tang, so the finished flavour is a little flatter.
1 cup buttermilk = 3/4 cup plain yogurt + 1/4 cup milk or water, whisked smooth
Yogurt carries the same lactic acid and live cultures, so it brings both the pH and the genuine cultured tang; the added liquid brings it back to pourable buttermilk consistency.
Trade-offSlightly richer than buttermilk — batters may want a splash more liquid.
1 cup buttermilk = 1 cup unsweetened soy or oat milk + 1 tbsp lemon juice or vinegar
Soy milk curdles most convincingly of the plant milks because it has enough protein to actually coagulate; the acid does the same pH job it does in dairy.
MethodRest 5-10 minutes as with dairy milk. Use an unsweetened, unflavoured variety.
Trade-offAlmond and rice milk are too thin to curdle properly and give a weaker result than soy or oat.
BakingVeganVegetarianDairy-freeEgg-freeNut-free
Allergen checkSoy milk introduces soy and many oat milks are not certified gluten-free. Check the carton, and for a severe allergy confirm the specific product with the manufacturer rather than trusting a category rule.
Cream of tartar + milk
Reliable
1 cup buttermilk = 1 cup milk + 1 3/4 tsp cream of tartar
Cream of tartar is a dry acid, so it lowers the milk's pH without adding the flavour that lemon or vinegar carries.
MethodWhisk the cream of tartar into a few tablespoons of the milk first to prevent lumps, then stir into the rest.
Trade-offCleanest-tasting of the acid swaps, but it will not thicken the way lemon does.
Every acid-plus-milk version is a stand-in for buttermilk's chemistry, not its flavour. In a recipe where buttermilk is the headline — buttermilk biscuits, buttermilk fried chicken, ranch dressing — the real thing is worth the trip.
Cooking around an allergy? Diet tags here describe the ingredient itself, not any particular brand. Processed products change formulation without notice and shared production lines are common, so read the label on everything you use. A severe allergy is a medical matter — confirm with the manufacturer or your clinician rather than relying on a substitution chart.