How to Make Buttermilk, and Which Substitute to Use

To make buttermilk, stir 1 tablespoon of lemon juice or distilled white vinegar into 1 cup of milk and leave it for 10 to 15 minutes, until it thickens very slightly and starts to curdle. That is the ratio and the timing King Arthur Baking gives, and the result replaces buttermilk cup for cup. It brings the acid a recipe needs, which matters most when the recipe uses baking soda, but less of the tang and body of cultured buttermilk. In King Arthur's test, Greek yogurt thinned with milk came closer on flavor.

How to make buttermilk with lemon juice or vinegar

1. Pour 1 cup (about 240 ml) of milk into a measuring jug.
2. Stir in 1 tablespoon (15 ml) of lemon juice or distilled white vinegar.
3. Leave it on the counter for 10 to 15 minutes. It is ready when it looks a little thicker and you can see small flecks of curd. It will stay thinner than store-bought buttermilk.
4. Stir it and use it in place of the same amount of buttermilk.

Some recipes put the acid in the cup first and pour milk up to the 1-cup line, which uses a tablespoon less milk. Both versions work. Wikipedia's buttermilk entry gives the metric version as about 15 ml of acid to 200 to 250 ml of milk.

Check the spoon if you are in Australia. An Australian tablespoon holds 20 ml, not 15, according to Wikipedia's tablespoon entry, so measure 3 teaspoons of acid instead.

Lemon juice or vinegar?

Either one sours the milk, and baking soda reacts with both. In King Arthur's biscuit test, the biscuits made with vinegar-soured milk rose and browned like the buttermilk batch but lacked its depth of flavor; lemon juice was not part of that test. Use white vinegar when you want nothing extra in the flavor, and lemon juice where a little citrus belongs, such as pancakes or a lemon loaf.

How long to let it stand

King Arthur says 10 to 15 minutes, and Wikipedia says about 10. If you make it ahead, put it in the fridge. The USDA's Food Safety and Inspection Service says food should never be left out of refrigeration for more than 2 hours, or 1 hour above 90 °F, because bacteria grow fastest between 40 °F and 140 °F.

Does it work with skim, 2% or whole milk?

Yes. Wikipedia says milk with any amount of fat can be used, though whole milk is the usual choice for baking. Most recipes were written for a leaner buttermilk than that: King Arthur's baking team, answering a reader under its test, says store buttermilk is almost always low-fat. Wikipedia's comparison table, drawn from USDA FoodData Central, puts low-fat buttermilk at 1.1% fat and whole milk at 3.2%. So soured 1% or 2% milk is the closest match, whole milk gives a slightly richer version, and skim works too.

Dairy-free buttermilk with plant milk

The same tablespoon of acid works in a cup of unsweetened plant milk, and how much it thickens depends on protein. In dairy milk, Wikipedia explains, falling pH makes casein, the main milk protein, clump together. USDA FoodData Central lists unsweetened soymilk at 2.86 g of protein per 100 g, close to dairy milk's 3.3 g, and unsweetened shelf-stable almond milk at 0.4 g. With about a seventh of soy's protein, almond milk will stay thin. It still delivers the acid, and the acid is the part baking soda needs.

What buttermilk is, and what the homemade version leaves out

Traditional buttermilk is the thin liquid left after cream is churned into butter. King Arthur notes it has not been commonly sold in grocery stores since the 1920s, when cultured buttermilk replaced it: low-fat or skim milk inoculated with bacteria that sour and thicken it. Wikipedia names the usual cultures as Lactococcus lactis or Lactobacillus bulgaricus, which make lactic acid, plus Leuconostoc citrovorum for the buttery flavor. In the US, the federal standard for cultured milk, 21 CFR 131.112, sets a minimum acidity of 0.5%, measured as lactic acid.

Milk soured with lemon juice or vinegar has none of those bacteria, and Wikipedia calls it acidified buttermilk. It has the acid that reacts with baking soda. It lacks the cultured flavor, and it is thinner: King Arthur's soured milk "thickens very slightly", while the bacteria in cultured buttermilk make it thicker than plain milk.

What's a substitute for 1 cup of buttermilk?

Each of these replaces 1 cup. King Arthur tested several side by side in biscuits, pancakes and a cake, against real buttermilk and plain 1% milk.

• Milk and acid: 1 cup of milk with 1 tablespoon of lemon juice or white vinegar, left for 10 to 15 minutes. It is the quickest, and its acid reacts with baking soda the way buttermilk's does.
• Greek yogurt and milk: 1 part Greek yogurt to 2 parts 1% or skim milk, so about 1/3 cup of yogurt whisked into 2/3 cup of milk. That is King Arthur's ratio. In its test this came second to real buttermilk in biscuits and tied with it in pancakes.
• Plain yogurt: thin it with milk or water until it pours like heavy cream. About three parts yogurt to one part milk is a reasonable place to start.
• Sour cream: thin it the same way, starting from about equal parts sour cream and milk. US rules (21 CFR 131.160) require sour cream to contain at least 18% milkfat, against 1.1% for low-fat buttermilk, so expect a richer result.
• Kefir: plain, unsweetened kefir goes in cup for cup. Wikipedia describes it as a fermented milk drink similar to a thin yogurt, so it arrives pourable and tangy.
• Cream of tartar: 1 3/4 teaspoons in 1 cup of milk, shaken until it dissolves. In King Arthur's biscuit test it lacked depth of flavor, like the vinegar version.
• Buttermilk powder: mixed with water as the package directs. King Arthur says it works as well as the soured-milk options and reacts well with leaveners, though it lacks the flavor of fresh buttermilk.

Which one to pick

King Arthur's conclusions from the test make a practical guide:

• The shorter the ingredient list, the more a substitute shows. In biscuits and pancakes, where there is little besides flour, fat and egg, thinned Greek yogurt was the best stand-in.
• The less buttermilk a recipe uses, the less the swap matters. For 1/4 cup in a chocolate cake, King Arthur says even plain milk will probably be fine.
• In its farmhouse buttermilk cake, with brown sugar, vanilla and nuts, every substitute worked except plain milk.
• Where buttermilk is the main ingredient, as in buttermilk ranch dressing or a cold buttermilk soup, buy cultured buttermilk.

Why buttermilk matters in baking

Buttermilk is acidic, and baking soda needs an acid to work. When sodium bicarbonate meets an acid it releases carbon dioxide, and that gas lifts soda bread, pancakes and biscuits. Wikipedia's sodium bicarbonate entry lists the acids that set it off, and they cover every option above: lactic acid (the acid in buttermilk, yogurt and kefir), cream of tartar, citric acid and vinegar.

Without an acid, the same entry says, heat breaks baking soda down into sodium carbonate, which "gives the baked product a bitter, soapy taste and a yellow color." That is why plain milk failed King Arthur's cake test: the farmhouse cake is leavened with baking soda, and made with plain 1% milk it came out darker and denser than the buttermilk one.

Recipes that rise on baking powder alone are more forgiving. Baking powder is "a mixture of a carbonate or bicarbonate and a weak acid", in Wikipedia's definition, so it carries its own acid. In King Arthur's baking powder biscuits, every version rose and browned, plain milk included, and only the flavor told them apart.

Buttermilk substitute for fried chicken

Buttermilk has two jobs in fried chicken. As a soak, it can make the meat more tender. As a dip, it is the wet layer that holds the flour coating on. A homemade substitute does the dipping job well, while the evidence for the soak comes from real buttermilk.

In a 2020 study in the journal Animals, Augustyńska-Prejsnar and colleagues marinated breast meat from hens at the end of their laying period, older birds than the chicken sold for frying, in buttermilk for 24 and 48 hours. Both soaks lowered the shear force, a lab measure of how hard meat is to cut, and reduced hardness and chewiness against unmarinated meat. The 24-hour soak improved the odor, flavor and tenderness of the roasted meat, and at 48 hours it became less palatable. The study used buttermilk and acid whey, not milk soured with lemon or vinegar, so for an overnight soak, store-bought buttermilk or a cultured stand-in such as kefir or thinned yogurt is closer to what was tested.

Keep any soak in the fridge. Food safety guidance from University of Wisconsin-Madison Extension is to always marinate food in the refrigerator, never at room temperature, and to cook poultry to 165 °F.

How the Nashville hot chicken sandwiches use it

The Nashville hot chicken sandwiches on this site put the buttermilk in the wet dip of a double dredge, and the recipe's FAQ adds that the chicken can be brined a day ahead. Chicken breasts are cut into filets about the size of the buns and patted dry. The wet bowl is 3/4 cup of buttermilk whisked with 1 large egg, 2 tablespoons of hot sauce, 1/4 cup of pickle juice and 1 teaspoon of baking powder, and 3 to 4 tablespoons of it get mixed into the seasoned flour to create a flaky texture. Each filet goes into the flour, then the wet mix, then the flour again, rests 10 to 15 minutes, and fries at about 350°F for 7 to 8 minutes, flipped halfway.

The FAQ already gives the swap: stir a tablespoon of lemon juice or white vinegar into a cup of regular milk and let it sit for about 10 minutes. In this batter, that changes four things, most of them small.

• Amount: the batter needs 3/4 cup. Make the FAQ's full cup and use 3/4 of it, or scale it to 3/4 cup of milk with 2 1/4 teaspoons of acid.
• Thickness: soured milk is thinner than cultured buttermilk, so a little less of it clings on the way through. The egg in this wet mix gives it body, which makes the difference smaller than in a recipe that dips chicken in buttermilk alone.
• The flaky bits: a thinner liquid soaks into flour faster. Add the 3 to 4 tablespoons a spoonful at a time and stop once the flour looks shaggy, before it turns to paste.
• Flavor: King Arthur found that buttermilk's taste "tends to disappear" against strong competing flavors. This batter has pickle juice and hot sauce, the flour carries chili powder and dry mustard, and the fried filets are dunked in an oil spiced with cayenne and brown sugar, so a cultured tang would be hard to pick out.

The rise stays the same. The recipe puts baking powder in both bowls, and baking powder brings its own acid.

Once the raw chicken has been through the wet mix and the flour, throw away whatever is left of both. The rest of a crisp crust is technique: a dry filet, a seasoned coating and oil at the right heat. The secret to crispy chicken parm guide walks through the same rules for a breaded cutlet.

What can I use buttermilk for?

Mostly baking and frying. Pancakes, biscuits and cake were the three King Arthur tested. Wikipedia adds soda bread, where buttermilk's acid is the partner for the baking soda, and marinades, especially for chicken and pork. Utah State University Extension lists pancakes, biscuits, dressings, pies, ice cream, cornbread and vinaigrettes, and suggests it with meat or cooked vegetable dishes. Buttermilk is also a drink: in Arab culture, Wikipedia says, it is sold ice cold and often drunk during Ramadan at iftar and suhur.

Can you make real cultured buttermilk at home?

Yes, with live cultures and a day or two. Utah State University Extension starts with 1 quart of whole milk and a packet of buttermilk starter culture, fermented in jars in an incubator or yogurt maker until the pH reaches 4.6 or lower. That first batch takes 18 to 48 hours, and USU says to discard it if it has not fermented within 48. After that, 1/4 cup of the finished buttermilk cultures the next quart in 8 to 12 hours. A pH strip or meter tells you when it is done, so for a recipe tonight, the lemon or vinegar method is the practical one.

How long homemade buttermilk keeps

Store-bought cultured buttermilk keeps 1 to 2 weeks in the fridge, according to the storage chart from Kansas State University Research and Extension by Karen Blakeslee, revised June 2026. The chart says to cover it tightly, remix it before using and check the date on the carton.

Neither that chart nor FoodSafety.gov's cold storage chart gives a separate time for milk soured with lemon or vinegar. It is still milk with acid stirred in, so treat it like the milk it came from: make it when you need it, cover and refrigerate any leftover, and use it before the date on the milk carton, which is how long K-State gives fresh milk.

Can you freeze buttermilk?

Yes. K-State gives buttermilk 3 months in the freezer. King Arthur suggests freezing buttermilk in 1/2-cup portions, and PJ Hamel, who ran its substitute test, wrote in reply to a reader that she has frozen it in an ice cube tray. It separates as it thaws. K-State says to remix it and Hamel says it is still fine to use in a recipe, so save thawed buttermilk for baking, marinades and batters. Label each portion with the amount and the date.

Those freezer times measure quality. FoodSafety.gov says food kept frozen continuously at 0 °F (-18 °C) or below stays safe indefinitely.