Baking Soda and Cream of Tartar Substitute for Baking Powder Guide
To replace 1 teaspoon of baking powder, mix ½ teaspoon cream of tartar with ¼ teaspoon baking soda. This is the most reliable homemade baking powder, because both parts are dry, measurable powders. It is single-acting, so put the batter in the oven soon after mixing.
Conversion chart
| Baking powder needed | Cream of tartar | Baking soda |
|---|---|---|
| ½ tsp | ¼ tsp | ⅛ tsp |
| 1 tsp | ½ tsp | ¼ tsp |
| 2 tsp | 1 tsp | ½ tsp |
| 1 tbsp (3 tsp) | 1½ tsp | ¾ tsp |
Why this pair works
Cream of tartar (potassium bitartrate) is a dry acid left over from winemaking. Commercial baking powder is simply baking soda plus a dry acid, and before modern acid salts were invented, that acid often was cream of tartar. So this mix is not just a substitute, it is the original baking powder.
The 2:1 ratio of cream of tartar to soda is roughly what it takes to neutralise the soda fully. That means no soapy aftertaste and no sour tang.
Homemade vs store-bought baking powder
| Cream of tartar + soda | Supermarket baking powder | |
|---|---|---|
| When it reacts | Mostly as soon as it gets wet | Double-acting: once when wet, again in the oven |
| Bench time | Bake within about 10 minutes | Batter can wait a bit longer |
| Taste | Clean, no metallic note | Some brands leave a slight metallic taste |
| Storage | Mix fresh, or add cornflour to store it | Shelf-stable for months |
Making a jar to keep
Mix 2 tbsp cream of tartar, 1 tbsp baking soda and 1 tbsp cornflour (cornstarch). Sift them together twice so they are evenly blended. The cornflour absorbs moisture and stops the acid and base reacting in the jar. Store it airtight and use it 1:1 in place of baking powder. Mixed this way it keeps well for a couple of months. Test it before using (½ tsp in hot water should fizz hard).
Tips for good results
- Whisk the mix thoroughly into the flour. Pockets of soda leave brown, bitter specks.
- Heat the oven and prepare the tins before adding liquid.
- For scones and biscuits, cut and bake straight away instead of chilling the shaped dough.
- If the recipe already contains buttermilk or yogurt, you can cut the cream of tartar by half.
Other things cream of tartar does
A pinch of cream of tartar stabilises whipped egg whites for meringue, prevents sugar syrups from crystallising, and gives snickerdoodles their tang. For more on the pair, see cream of tartar and baking soda uses.
No cream of tartar? Try baking soda and vinegar instead.
Frequently Asked Questions
Mix 2 parts cream of tartar with 1 part baking soda. For 1 teaspoon of baking powder, use ½ tsp cream of tartar and ¼ tsp baking soda.
It is about as strong, but it reacts faster. Bake soon after mixing for the best rise.
Only if you are making a batch to store. It absorbs humidity so the mix does not react in the jar.