Use milk and lemon juice instead of buttermilk at 1 tbsp lemon juice per cup of milk, rested 5 minutes. Buttermilk and milk and lemon juice do similar work in a recipe, but they are not identical, and the ratio is what makes the swap succeed. This guide gives the exact ratio, an equivalence table for every amount you will need, what changes in the finished dish, and when you should not make the swap at all. All ratios on this page come from the CookScale substitution data, and every result is approximate; taste the dish before serving, and adjust the seasoning if the swap changes the flavour.
Buttermilk to Milk and lemon juice: equivalence table
The table below scales the ratio — 1 tbsp lemon juice per cup of milk, rested 5 minutes — to every amount you will need, from a quarter of a cup up to three cups. Use the row that matches your recipe, and do not guess the scaling in your head, because a small error in the ratio grows with the size of the recipe.
| Buttermilk needed | Milk | Lemon juice | Rest |
|---|---|---|---|
| 1/4 cup | 1/4 cup | 3/4 tsp | 5 minutes |
| 1/2 cup | 1/2 cup | 1 1/2 tsp | 5 minutes |
| 1 cup | 1 cup | 1 tbsp | 5 minutes |
| 2 cups | 2 cups | 2 tbsp | 5 minutes |
| 3 cups | 3 cups | 3 tbsp | 5 minutes |
When a recipe calls for an amount that is not in the table, scale the ratio proportionally: work out how many cups of buttermilk the recipe needs, then multiply the ratio by that number. For a single cup, the ratio is exactly as stated; for half a cup, halve it; for two cups, double it. Keep the recipe scaler open while you cook, and you can scale the whole recipe, including the substitution, in one step.
What changes when you use milk and lemon juice instead of buttermilk
Milk soured with lemon juice behaves almost exactly like buttermilk in baking, because the acid does the same work: it activates the baking soda, tenderises the crumb and adds a tang. The main difference is the flavour: lemon juice adds a faint citrus note, which suits a lemon cake or a pancake, but can be noticeable in a plain biscuit. The texture is also slightly different: soured milk is thinner than cultured buttermilk, which is thick and creamy, so a batter made with soured milk may be a little thinner. The rise is the same, because the acid activates the baking soda in exactly the same way, and the crumb is just as tender. In a dressing or a marinade, the difference is bigger, because real buttermilk is thicker and richer, while soured milk is thin and sharp.
When not to substitute buttermilk with milk and lemon juice
Do not use plain milk — without acid, baking soda will not activate and the bake can taste soapy. That rule is the most important part of this page, because a substitution that works in one recipe can fail badly in another. Buttermilk does a specific job in each recipe, and the swap only works when the substitute can do the same job. In a recipe where buttermilk is the main structure — where it holds the bake together, or where its flavour is the point of the dish — the substitute will not do, and it is better to wait until you have the real ingredient, or to choose a different recipe. In a recipe where buttermilk is a supporting ingredient, where it adds moisture, richness or flavour but does not carry the dish, the swap usually works well. The test is simple: if removing the buttermilk would ruin the recipe, do not substitute it; if the recipe would still work without it, the substitute is probably safe.
Why this swap works
The acid in buttermilk activates baking soda and tenderises crumb; any acidic milk works the same way. That is the principle behind the swap: the substitute does the same chemical or structural job as the original, even though it looks and tastes different. The acid in an acidic substitute activates baking soda, the fat in a fatty substitute shortens a dough, and the liquid in a liquid substitute hydrates the flour. When the substitute does the same job, the swap works; when it does a different job, the swap fails. The ratio on this page is the amount that makes the substitute do the same job as the original, and it is worth following exactly, rather than guessing, because a small error in the ratio changes the job the substitute does.
Worked examples: buttermilk to milk and lemon juice in real recipes
1. Buttermilk pancakes on a Sunday morning
A stack of pancakes for four needs a cup of buttermilk, so stir a tablespoon of lemon juice into a cup of milk and leave it for five minutes. The milk thickens slightly and may curdle a little, which is normal. Pour the soured milk into the batter exactly where the buttermilk would have gone, and cook the pancakes over a medium heat. The lemon adds a faint citrus note that suits pancakes, and the acid activates the baking powder, so the pancakes turn out light and fluffy.
2. A batch of buttermilk biscuits
A batch of buttermilk biscuits needs two cups of buttermilk, so stir two tablespoons of lemon juice into two cups of cold milk and leave it in the fridge for five minutes. The cold soured milk keeps the butter cold in the dough, which is what makes the biscuits flaky, so use milk straight from the fridge and work quickly. Cut the biscuits and bake them in a hot oven, and the acid in the milk will help them rise.
3. A buttermilk fried chicken marinade
A fried chicken marinade for four needs a cup of buttermilk, so stir a tablespoon of lemon juice into a cup of milk and leave it for five minutes. The soured milk tenderises the chicken in the same way as buttermilk, because the acid breaks down the proteins, and the chicken should marinate for at least an hour, or overnight for the best result. The marinade will be thinner than a buttermilk marinade, so turn the chicken halfway through to coat it evenly.
How to make the swap
Pour the milk into a measuring jug, stir in the lemon juice, and leave the jug on the counter for five minutes. The milk will thicken slightly and may curdle a little, which is normal and exactly what you want: the curdling shows that the acid is working. Use the soured milk straight away, before it separates too much, and stir it into the batter exactly where the buttermilk would have gone. Use fresh lemon juice if you have it, because bottled lemon juice works but tastes slightly sharper. Do not skip the resting time, because the acid needs a few minutes to work on the milk. For a biscuit or a scone, the soured milk should be cold, so use cold milk from the fridge and let it rest in the fridge rather than on the counter.
Common mistakes
The most common mistake is skipping the resting time and using the milk straight away, before the acid has had time to work. Rest it for five minutes, or the baking soda will not activate properly. The second mistake is using plain milk without any acid, which leaves the baking soda unactivated and the bake tasting soapy. Always add the acid. The third mistake is using too much lemon juice, which makes the bake taste of lemon and can make the crumb too tender; one tablespoon per cup is enough. Finally, do not use this swap in a recipe where the thickness of buttermilk matters, such as a ranch dressing, because soured milk is too thin and the dressing will be runny.
Frequently asked questions
How much lemon juice do I add to milk to make buttermilk?
Add 1 tablespoon of lemon juice per cup of milk, and rest the mixture for 5 minutes. The milk thickens slightly and may curdle a little, which is normal and shows the acid is working. Use the soured milk straight away, before it separates too much, and stir it into the batter exactly where the buttermilk would have gone.
Can I use bottled lemon juice instead of fresh?
Yes, bottled lemon juice works, but it tastes slightly sharper than fresh lemon juice, so the bake may have a faintly sharper tang. Fresh lemon juice is better if you have it, because its flavour is cleaner. Either way, use the same amount: one tablespoon per cup of milk, rested for five minutes.
Why does the milk curdle when I add lemon juice?
Because the acid in the lemon juice makes the proteins in the milk clump together, which is exactly what happens when buttermilk is cultured. The curdling is normal and it shows the acid is working. Stir the soured milk before you use it, and do not worry about the small curds, because they disappear into the batter.
Can I use this swap in a dressing or a marinade?
Yes, for a marinade, where the acid tenderises the meat in the same way as buttermilk. For a dressing, the swap is less good, because soured milk is thinner than cultured buttermilk, so a ranch dressing made with soured milk will be runny. For dressings, yogurt is a better substitute, because it is thicker.
What happens if I use plain milk instead of buttermilk?
The bake will not rise properly, and it may taste soapy. Buttermilk is acidic, and the acid activates the baking soda; plain milk has no acid, so the baking soda stays unactivated and leaves a soapy taste. Always add an acid, such as lemon juice or vinegar, when you substitute for buttermilk in a recipe that uses baking soda.