Use cream of tartar and milk instead of buttermilk at 1 3/4 tsp cream of tartar per cup of milk. Buttermilk and cream of tartar and milk 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 Cream of tartar and milk: equivalence table
The table below scales the ratio — 1 3/4 tsp cream of tartar per cup of milk — 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 | Cream of tartar |
|---|---|---|
| 1/4 cup | 1/4 cup | 1/2 tsp |
| 1/2 cup | 1/2 cup | 1 tsp |
| 1 cup | 1 cup | 1 3/4 tsp |
| 2 cups | 2 cups | 3 1/2 tsp |
| 3 cups | 3 cups | 5 1/4 tsp |
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 cream of tartar and milk instead of buttermilk
Milk soured with cream of tartar behaves like buttermilk in baking, because the cream of tartar is an acid that activates the baking soda and tenderises the crumb. The main difference is the flavour: cream of tartar adds no tang of its own, so the bake tastes cleaner and less sour than a buttermilk bake, which suits a plain cake or a scone. The texture is also slightly different: soured milk is thinner than cultured buttermilk, so a batter made with it 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 has no cultured flavour.
When not to substitute buttermilk with cream of tartar and milk
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 cream of tartar and milk in real recipes
1. A plain sponge cake that needs buttermilk
A sponge cake needs a cup of buttermilk, so whisk 1 3/4 teaspoons of cream of tartar into a cup of milk and leave it for a few minutes. The cream of tartar adds acid without adding any flavour of its own, so the cake tastes clean and plain, which suits a sponge that will be filled with jam and cream. Whisk the mixture well, so the cream of tartar dissolves completely, and pour it into the batter exactly where the buttermilk would have gone.
2. A batch of scones with cream of tartar
A batch of scones needs two cups of buttermilk, so whisk 3 1/2 teaspoons of cream of tartar into two cups of milk and leave it for a few minutes. The acid activates the baking soda and helps the scones rise tall, and the clean flavour suits a plain scone that will be served with jam and cream. Chill the soured milk after mixing, so the butter stays cold in the dough, and work quickly when you cut the scones.
3. Buttermilk pancakes without lemons or vinegar
A stack of pancakes for four needs a cup of buttermilk, and there is no lemon or vinegar in the house, so whisk 1 3/4 teaspoons of cream of tartar into a cup of milk and leave it for a few minutes. The milk thickens slightly and the acid activates the baking powder, so the pancakes turn out light and fluffy. Whisk the mixture well, so no gritty specks remain, and pour it into the batter exactly where the buttermilk would have gone.
How to make the swap
Pour the milk into a measuring jug, whisk in the cream of tartar until it dissolves, and leave the jug for a few minutes before use. The cream of tartar dissolves best in warm milk, so use milk at room temperature rather than cold from the fridge, and whisk it well, because undissolved cream of tartar leaves gritty specks in the batter. Use the soured milk straight away, and stir it into the batter exactly where the buttermilk would have gone. Do not skip the whisking step, because the cream of tartar needs to dissolve fully to work. For a biscuit or a scone, chill the soured milk after mixing, so the butter stays cold in the dough.
Common mistakes
The most common mistake is not whisking the cream of tartar in properly, which leaves gritty white specks in the finished bake. Whisk it until it dissolves completely, and use milk at room temperature, which helps it dissolve. The second mistake is using too much cream of tartar, which makes the bake taste metallic and can make the crumb too tender; 1 3/4 teaspoons per cup is enough. The third mistake is using plain milk without any acid, which leaves the baking soda unactivated and the bake tasting soapy. Always add the acid. Finally, do not use this swap in a recipe where the thickness or the tang of buttermilk matters, such as a ranch dressing, because soured milk is too thin and too plain.
Frequently asked questions
How much cream of tartar do I add to milk to make buttermilk?
Add 1 3/4 teaspoons of cream of tartar per cup of milk, whisked in until it dissolves. The cream of tartar is an acid, so it soured the milk and activates the baking soda in the same way as buttermilk. Use milk at room temperature, which helps the cream of tartar dissolve, and whisk it well, because undissolved cream of tartar leaves gritty specks in the batter.
Does cream of tartar and milk taste like buttermilk?
No, not exactly. Cream of tartar adds acid without adding any flavour of its own, so the bake tastes cleaner and less sour than a buttermilk bake. The rise and the tenderness are the same, because the acid does the same work, but the tang is missing, which suits a plain cake or a scone better than a rich, tangy bake.
Why does my bake have gritty white specks?
Because the cream of tartar did not dissolve fully before it went into the batter. Whisk it into milk at room temperature until it dissolves completely, and do not add it to cold milk, where it dissolves slowly. If the specks are already in the batter, there is no fix, but the bake is still safe to eat, and the specks are harmless.
Can I use this swap in a dressing or a marinade?
It is better not to. Soured milk made with cream of tartar is thin and has no cultured flavour, so a ranch dressing made with it will be runny and plain, and a marinade will be less effective than buttermilk or yogurt. For dressings and marinades, yogurt or kefir are better substitutes, because they are thicker and tangier.
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 cream of tartar, lemon juice or vinegar, when you substitute for buttermilk in a recipe that uses baking soda.