Buttermilk Substitute: What to Use and the Exact Ratios

Updated August 2026 · Baking Resources

Add 1 tablespoon of white vinegar or lemon juice to a liquid measuring cup, then fill it to the 1 cup line with milk. Stir once and let it sit 5 to 10 minutes, until the surface looks slightly thickened and a little curdled. That is the standard buttermilk substitute, and it works in nearly every baking application, including pancakes, biscuits, cakes, muffins, and cornbread.

Not sure how much acid you need for a partial cup? Our free substitutions finder does the math for any amount in seconds.

Updated August 2026

Why buttermilk matters in the first place

Most swap charts tell you buttermilk adds "tang" and stop there. That undersells it, and it's the reason so many substitutions go wrong.

Buttermilk does two separate jobs in a batter.

Job one: it's an acid. Real cultured buttermilk sits around pH 4.5. When that acid meets baking soda, the two react and release carbon dioxide, which is what lifts your pancakes and biscuits. Baking soda on its own is a pure base. It cannot make gas without an acid partner.

Job two: it tenderizes. The same acidity weakens gluten strands as they form and helps the proteins in the flour set a little softer. That's the fine, plush crumb you get in a buttermilk cake versus the slightly chewier one you get with plain milk.

Here's the part that trips people up. If you swap in plain milk with no added acid, and your recipe leans on baking soda for lift, you get two problems at once. The batter barely rises, because there's nothing for the soda to react with. And the unreacted soda stays in the finished bake, where it tastes soapy, metallic, and faintly bitter. That flat, slightly off cornbread is almost always this exact mistake.

So the goal of any buttermilk replacement isn't just matching the liquid volume. It's matching the acid.

Buttermilk substitute chart: every swap and the exact ratio

All ratios below make 1 cup. Pick based on what's already in your fridge.

Whole milk gives the best texture, but 2 percent, 1 percent, and skim all work. Lower-fat milk curdles faster and looks thinner, which is normal and doesn't hurt the rise.

Be honest about what the vinegar version is and isn't

The milk plus vinegar trick is often described as "homemade buttermilk." It isn't, quite, and you should know the difference before you use it.

Real buttermilk is cultured. Live bacteria fermented lactose into lactic acid over hours, which builds both a mellow, layered tang and a genuinely thick body. What you make in 10 minutes with vinegar is acidulated milk. It's thin, it's sharper and flatter in flavor, and the curds are loose rather than smooth.

For baking, that difference barely shows. The acid is there, the soda reacts, and the crumb tenderizes. Pancakes, biscuits, cakes, waffles, muffins, and cornbread all come out excellent.

Where it falls short is anywhere buttermilk is the flavor you're tasting, not the chemistry you're using. A buttermilk salad dressing, a buttermilk marinade, or a cold buttermilk soup will taste thin and vinegary. For those, use kefir or thinned plain yogurt instead. Both are actually cultured, so the tang has depth.

One more honest note. Acidulated milk supplies a bit less total acid than an equal volume of cultured buttermilk. In a recipe that's heavy on baking soda, you may notice a slightly lower rise. It's a small difference, and it's rarely enough to change your plans, but it's real.

How much acid your baking soda actually needs

This is the table that makes every substitution obvious. Baking soda needs a partner. Here's roughly how much of each acid it takes to react with a given amount.

Notice how much liquid acid 1 teaspoon of soda demands. That's why well-written recipes almost never call for more than about 1/2 teaspoon of baking soda per cup of buttermilk. If you find one that does, the extra soda is usually there on purpose to raise the pH for browning, not for lift.

What if the recipe only lists baking powder?

You can still use buttermilk, and it usually improves the result. Baking powder already contains its own acid, so it doesn't need the buttermilk to work. You get the tenderizing benefit and the tang for free.

The one catch is that extra acid slightly slows a double-acting baking powder and can mute the rise a little. If the recipe uses baking powder only and you're swapping in buttermilk for the milk, add 1/4 teaspoon of baking soda per cup of buttermilk and cut the baking powder by 1/2 teaspoon. That rebalances it.

Partial amounts: the numbers nobody gives you

Almost every chart online gives you the 1 cup version and leaves you doing fraction math at the counter. Here are the exact acid measurements for the amounts recipes actually call for.

The rule underneath the whole table is simple: 3/4 teaspoon of acid per 1/4 cup of milk. Everything else is just scaling.

If you'd rather work in tablespoons than cups, our cups to tablespoons converter will translate any of these instantly.

Always put the acid in the cup first, then pour the milk on top. Doing it the other way means guessing at the total volume, and you'll end up with more liquid than the recipe wants.

Worked example: biscuits calling for 3/4 cup buttermilk

Say you're making a batch of drop biscuits. The recipe asks for 2 cups flour, 1 tablespoon baking powder, 1/2 teaspoon baking soda, 1/2 teaspoon salt, 6 tablespoons cold butter, and 3/4 cup buttermilk. You have milk and a bottle of white vinegar.

Step 1. Pour 2 1/4 teaspoons of white vinegar into a liquid measuring cup. That's the 3/4 cup row from the table above.

Step 2. Add whole milk until the liquid reaches the 3/4 cup line. Not 3/4 cup of milk plus the vinegar. The vinegar counts toward the total.

Step 3. Stir once and set it aside for 10 minutes while you cut the butter into the flour. When it's ready, the surface will look slightly grainy and the mixture will coat the side of the cup a little.

Step 4. Use it exactly where the recipe says buttermilk.

What to expect versus real buttermilk. The dough will be a touch looser, because acidulated milk is thinner than the cultured stuff. Rise will be roughly the same, maybe a hair lower, since the recipe's baking powder is doing most of the lifting and the 1/2 teaspoon of soda has plenty of acid to work with. The crumb will still be soft and tender. The main difference you'll taste is a slightly milder tang.

If you want that dough back to normal thickness, hold back about 1 tablespoon of the liquid and add it only if the dough looks dry.

Storing buttermilk so you stop needing a substitute

Buttermilk keeps longer than people assume, and it freezes beautifully.

In the fridge. Unopened, it's good until the date on the carton. Once opened, use it within about 2 weeks, kept at 40°F or below on a shelf rather than in the door. Its acidity holds spoilage bacteria back better than plain milk does. Storage times for dairy are listed in the USDA's FoodKeeper guidance. Separation is normal, so shake before pouring. Thick clumps, mold, or a sour-beyond-tangy smell mean it's done.

In the freezer. This is the best trick in the article. Pour leftover buttermilk into a muffin tin or an ice cube tray, freeze solid, then bag the portions. Standard muffin cups hold about 1/2 cup each and ice cube compartments hold about 2 tablespoons. It keeps about 3 months. Thaw in the fridge overnight, expect it to look separated, and whisk it back together. Frozen and thawed buttermilk is only good for baking, not for drinking or dressings, because the texture breaks.

In the pantry. Buttermilk powder is the low-waste answer if you bake once a month. An unopened can keeps roughly a year in a cool cupboard. After opening, refrigerate it and use within about 3 months. Whisk 4 tablespoons of powder into your dry ingredients and add 1 cup of water where the recipe wants liquid. That method actually beats mixing the powder with water first, since it eliminates lumps entirely.

Quick troubleshooting

My milk didn't curdle. Ultra-pasteurized milk sometimes resists curdling. Give it 15 minutes. Even if it never looks curdled, the acid is still in there and will still react with the soda, so use it anyway.

It tastes like vinegar in the finished bake. You used too much acid, or your batter sat too long before baking. Measure the acid level with a spoon rather than free-pouring, and get the batter into the oven promptly.

My cake came out soapy. That's unreacted baking soda, which means the substitute didn't have enough acid, or you used plain milk with no acid at all. Check your amounts against the soda table above.

My biscuits are dense. Overworked dough is the usual culprit, not the buttermilk. But if you swapped in thinned yogurt or sour cream, the extra fat will also firm up the crumb slightly.

FAQ

How do I make buttermilk from regular milk?

Put 1 tablespoon of white vinegar or lemon juice in a measuring cup, fill it to the 1 cup line with any milk, stir, and wait 5 to 10 minutes. It'll thicken slightly and look a bit curdled. That's your signal it's ready to use in the batter.

Can I just use regular milk instead of buttermilk?

Only if the recipe gets all its lift from baking powder. If baking soda appears in the ingredient list, plain milk will give you a flat bake and a soapy aftertaste from the soda that never reacted. Adding 1 tablespoon of acid per cup fixes it in 10 minutes.

Is the vinegar version as good as real buttermilk?

For baking, close enough that most people can't tell. It's thinner and less tangy than cultured buttermilk, and it supplies slightly less acid, so a very soda-heavy recipe may rise a touch less. For dressings, dips, and marinades, use kefir or thinned yogurt instead.

What's the best dairy-free buttermilk replacement?

Unsweetened soy milk plus 1 tablespoon of acid per cup is the strongest performer, since its protein content lets it curdle and thicken almost like dairy. Almond milk works nearly as well. Oat milk gives the mildest flavor, and coconut milk works fine but carries coconut into the finished bake.

How much lemon juice do I use for 1/2 cup of buttermilk?

Use 1 1/2 teaspoons of lemon juice, then add milk up to the 1/2 cup line. The underlying rule is 3/4 teaspoon of acid for every 1/4 cup of milk, so you can scale it to any amount.

Can I use water instead of milk for making buttermilk?

Not with vinegar. Acid plus water gives you sour water, with none of the fat, protein, or sugar that build crumb and browning. The one exception is buttermilk powder, which is dried buttermilk solids and is designed to be mixed with plain water.

Does buttermilk substitute work in fried chicken or marinades?

It tenderizes, but the flavor comes out sharp and one-note. Thinned plain yogurt is the better choice for marinades because it's genuinely cultured and clings to the food. Save the vinegar method for batters and doughs.

How long does homemade buttermilk substitute last?

Use it the day you make it. Once you've soured milk with vinegar or lemon juice, it doesn't have the protective culture that real buttermilk has, so it just spoils like open milk. Mix only what your recipe calls for.

Related guides

• Baking Powder Substitute for when the leavening itself is what you're out of
• Heavy Cream Substitute for the other dairy swap that comes up constantly
• Substitutions Finder to look up any ingredient swap with exact ratios
• Cups to Tablespoons Converter for scaling the acid amounts above