Cream of tartar is one of those ingredients that appears only occasionally in recipes — but when it does, it's almost always doing something specific and important. Understanding its function lets you choose the right substitute for your situation.
Cream of tartar (potassium bitartrate) is a fine white powder — a natural acidic salt that forms as a byproduct of winemaking (it crystallizes on the inside of wine barrels). In baking it serves four main functions: stabilizing egg white foams, activating baking soda as a leavening acid, preventing sugar crystallization in candy and frosting, and adding a characteristic tangy flavor (most notably in snickerdoodles).
Cream of tartar lowers the pH of egg whites, which denatures proteins more evenly and stabilizes the foam structure. Meringues made without it can weep (release liquid) and are more prone to collapse.
Use 1/4 tsp white vinegar or lemon juice per 1/4 tsp cream of tartar (or per 3 egg whites). These acids lower egg white pH exactly as cream of tartar does. White vinegar is preferred because it's flavorless; lemon juice adds a subtle citrus note. Results are nearly identical to cream of tartar meringue.
💡 Note: you can often omit cream of tartar entirely in meringue if you're careful not to overwhip and bake promptly. It provides insurance against failure rather than being strictly necessary.
Cream of tartar is the acid in homemade baking powder: 1/4 tsp baking soda + 1/2 tsp cream of tartar = 1 tsp baking powder equivalent.
In candy making and frostings, cream of tartar's acidity inverts some of the sucrose into glucose and fructose, preventing large sugar crystals from forming (which makes fudge grainy or crystallizes caramel). Use for smooth fudge, pralines, and stable buttercream.
Use 1 tsp lemon juice per 1/2 tsp cream of tartar in candy/frosting applications. Citric acid performs the same inversion reaction. Corn syrup also prevents crystallization — replace 1/4 of the sugar in candy recipes with corn syrup for the same stabilizing effect.
In snickerdoodles, cream of tartar provides both leavening (with baking soda) and the characteristic tangy flavor. It also affects texture — cookies made with cream of tartar are chewier with a more distinctive crinkle.
Replace 1/2 tsp cream of tartar + 1/4 tsp baking soda with 1 tsp baking powder. The baking powder provides equivalent leavening. The tangy flavor will be absent — cookies will taste sweeter and more neutral. Add 1/2 tsp lemon zest or a few drops of lemon juice to approximate the tang.
| Application | Cream of Tartar Amount | Substitute | Notes |
|---|---|---|---|
| Meringue stabilizer | ¼ tsp per 3 egg whites | ¼ tsp white vinegar or lemon juice | Near-identical results |
| Leavening acid (with baking soda) | ½ tsp per 1 tsp baking powder | ½ tsp lemon juice or vinegar | Use with ¼ tsp baking soda |
| Candy crystallization prevention | ½ tsp per batch | 1 tsp lemon juice | Or replace ¼ sugar with corn syrup |
| Snickerdoodle flavor + leavening | ½ tsp + ¼ tsp baking soda | 1 tsp baking powder | Add lemon zest for tang |