What this calculator does
Self-raising flour is nothing more than plain flour with a raising agent already mixed in, so when a recipe calls for self-raising flour and only plain flour is on hand, the fix is straightforward: add baking powder. The standard ratio used across most baking references is 2 level teaspoons of baking powder per 150 g (roughly 1 cup) of plain flour.
This calculator scales that ratio to any quantity of plain flour, converting plain flour to self raising flour by showing exactly how much baking powder to whisk in, in both teaspoons and grams, plus an optional pinch of salt some recipes add alongside it.
The formula
The baking powder needed scales in direct proportion to the amount of plain flour: 2 teaspoons per 150 g. Dividing the flour amount by 150 and multiplying by 2 gives the teaspoons of baking powder needed, which is also converted to grams using the common reference that one level teaspoon of baking powder weighs about 4 g.
| Term | Meaning |
|---|---|
| Self-raising flour | Plain flour with a raising agent, usually baking powder, already blended in at a fixed ratio. |
| Baking powder | A raising agent combining an acid and a base that releases carbon dioxide when moistened and heated, making baked goods rise. |
| Plain flour | Wheat flour with no raising agent added, also called all-purpose flour in some regions. |
The inputs explained
| Field | What to enter |
|---|---|
| Plain flour (g) | The amount of plain flour you are starting with, in grams. |
When to use it
A recipe calls for self-raising flour and you only have plain
Rather than buying a separate bag of self-raising flour for one recipe, adding the right amount of baking powder to plain flour on hand gives the same result.
Scaling a recipe up or down
A recipe written for self-raising flour scales cleanly if you know the fixed ratio, since doubling the flour also doubles the baking powder needed, keeping the rise consistent at any batch size.
Running low on self-raising flour mid-recipe
Topping up a partial bag of self-raising flour with plain flour and a top-up of baking powder, calculated on just the plain portion added, keeps the overall mix at the right strength.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How much baking powder for common flour amounts?
A range of plain flour amounts and the baking powder needed to convert each to self-raising.
| Plain flour | Baking powder to add | Optional pinch of salt |
|---|---|---|
| 75 g | 1.00 tsp (about 4 g) | 0.13 tsp |
| 150 g | 2.00 tsp (about 8 g) | 0.25 tsp |
| 225 g | 3.00 tsp (about 12 g) | 0.38 tsp |
| 300 g | 4.00 tsp (about 16 g) | 0.50 tsp |
| 450 g | 6.00 tsp (about 24 g) | 0.75 tsp |
| 600 g | 8.00 tsp (about 32 g) | 1.00 tsp |
Questions
What is the standard ratio of baking powder to plain flour?
2 level teaspoons of baking powder per 150 g of plain flour, which is roughly 1 cup, is the ratio used across most published baking references for converting plain flour to self-raising flour.
Do I need to add salt as well?
Some self-raising flour blends include a small amount of salt, commonly around a quarter teaspoon per 150 g, but many home bakers leave it out and simply salt the recipe as they normally would. It is optional rather than essential to the flour raising properly.
Can I use this ratio for any recipe?
It works for standard baking such as cakes, scones and quick breads, which is what self-raising flour is designed for. Recipes with more specific raising requirements, such as certain bread or pastry recipes, are usually written for plain flour deliberately and should not be substituted.
Does the type of baking powder matter?
Most baking powder sold for home use is double-acting, releasing gas both when it is moistened and again when heated, and the 2 tsp per 150 g ratio assumes that standard type. A different formulation could need adjusting, so check the product's own instructions if it specifies otherwise.
For converting the weight of other baking ingredients to volume, see the grams to cups calculator. To go the other way, from a volume measure to weight, use the cups to grams calculator.