Buttermilk Substitute
Real substitutes for buttermilk, with exact ratios -- and it turns out the standard substitute is also just how buttermilk is actually made.
The substitutes
Real substitutes for 1 cup of buttermilk
Milk + lemon juice or vinegar
1 cup milk + 1 tablespoon lemon juice or white vinegar
Stir and let sit 5-10 minutes until slightly thickened before using. This is also just how to make buttermilk from scratch, not only a substitute -- real buttermilk is milk soured with an acid.
Plain yogurt
1 cup plain yogurt thinned with 1-2 tablespoons milk
Whisk until pourable; works well in most baked goods, and has a closer tang to real buttermilk than the milk + acid version.
Why recipes call for buttermilk
Buttermilk is acidic, and that acid does real work: it reacts with baking soda to help pancakes, biscuits, and cakes rise, and it tenderizes gluten for a softer crumb. That's why a splash of milk alone doesn't work as a substitute -- the substitute has to bring its own acid (lemon juice, vinegar, or yogurt's natural tang) to do the same job, not just add liquid.
Frequently Asked Questions
What can I use instead of buttermilk?
The most common substitute is 1 cup of milk plus 1 tablespoon of lemon juice or white vinegar, stirred and left to sit for 5-10 minutes until it slightly thickens and curdles. Plain yogurt thinned with a little milk also works well.
Does the buttermilk substitute taste the same?
It's close but not identical -- real buttermilk has a fuller tang from fermentation. The acid in the substitute reacts with baking soda the same way real buttermilk does, so baked goods rise correctly, even if the flavor is slightly milder. Thinned yogurt gets you closer to the real tang than the milk + acid version does.
Can I use any type of milk?
Whole or 2% milk works best; the fat content helps the substitute curdle and thicken properly. Skim milk works in a pinch but produces a thinner result.
Is making your own buttermilk the same as substituting it?
Practically, yes -- real buttermilk is traditionally just milk that's been soured with an acid (originally the liquid left over from churning butter). The milk + lemon juice/vinegar method is both the standard substitute and literally how homemade buttermilk is made.