Buttermilk Substitute Calculator
Out of buttermilk? Get the exact milk-plus-acid, yogurt or cream-of-tartar amounts to replace any quantity a recipe needs.
How it works
Milk + acid: 1 tbsp lemon juice or vinegar per cup, topped up with milk · Yogurt: ¾ cup yogurt + ¼ cup milk per cup · Cream of tartar: 1¾ tsp per cup of milk
Buttermilk does two jobs in a recipe: its acidity reacts with baking soda to create lift, and it adds tang and tenderness. A substitute only needs to restore that acidity, which is why a tablespoon of lemon juice or vinegar stirred into a cup of milk works — let it stand a few minutes and the milk thickens and sours. Plain yogurt thinned with milk gives an even closer body, and cream of tartar is a dry-pantry option. All of these keep the leavening reaction intact so your pancakes, biscuits and cakes still rise.
Worked example
A recipe needs 1 cup of buttermilk and you choose the milk-plus-lemon method. Add 1 tablespoon of lemon juice to a measuring cup, top up with milk to the 1-cup line, and rest for 5–10 minutes until it looks slightly curdled.
Frequently asked questions
Why does the milk need to sit before I use it?
The acid needs a few minutes to react with the milk proteins, thickening and souring it so it behaves like real buttermilk. Using it immediately skips that step and can leave the batter under-acidified.
Can I use plant-based milk?
Yes. Soy and other non-dairy milks curdle with lemon juice or vinegar much like dairy milk, so the same 1 tablespoon of acid per cup works. Results are best with unsweetened, unflavoured varieties.
Does the substitute change the leavening?
It keeps the acid that reacts with baking soda, so the lift is preserved. If your recipe uses baking soda specifically for the buttermilk’s acidity, any of these acidic substitutes will maintain the rise.
Related calculators
This calculator is for educational purposes. Double-check important results before acting on them.