One tsp of double acting baking powder to one cup of flour.
About 1.5 teaspoons. If the recipe calls for self raising flour and you don't have any then add 1.5 teaspoons of baking powder and 0.5 teaspoons of salt.
Generally you use 1 to 2 teaspoons of baking powder to each cup of flour.
One to one and a half teaspoons of baking powder and a pinc to one half teaspoon of salt to a cup (125 g) of flour.
Self raising flour makes the cake rise, but if you don't have any you can use plain flour and baking powder which has the same effect. 225g plain flour and 4 teaspoons baking powder, will transform it into self raising flour.
I don't know how much volume 4 oz. will be, but most recipes use the ratio of 1 teaspoon of baking powder to 1 cup of flour. Weigh the flour, measure it and find the amount of baking powder that way.
Baking powder - add two teaspoons of baking powder to each cup of plain flour. In America they call "plain flower" all "purpose flour", in Australia where I am from we have 2 main types Plain & self raising. :)
Add about a teaspoon of Baking Powder and one of Bicarbonate of Soda to the flour per pound of flour. If you find Baking Soda tastes bitter then you can add a tsp of Cream of Tartar instead. Or you could put say one and a half teaspoons of Baking Powder.
Hmmm. One can not substitute flour with baking powder. One can however substitute selfraising flour with ordinary flour and a few teaspoons of baking powder. (My best guess would be approx 1 teaspoon of baking powder per 150-200 grams of flour.)
For one cup of self-rising flour I use 1 cup all-purpose flour, and add: 1 1/4 teaspoons baking powder AND 1/8 teaspoons salt
For self rising flour 1 teaspoon.For biscuit mix 2 teaspoons.
Self-rising flour consists of flour, baking powder, and salt. So the flour here is ordinary flour to which you add bicarbonate of soda and salt. Baking powder is baking soda, an acid salt, and cornstarch (the effect is to create carbon dioxide when it is placed in a solution). To make self-rising flour, take one cup of flour and add one and a half (1 1/2) teaspoons of baking powder and 1/2 teaspoon of salt.
If a recipe calls for self-rising flour, your recipe will not turn out if you replace it with unbleached flour only because unbleached flour does not rise. You would also need to add baking powder to the recipe (about three teaspoons per cup of flour) if you were making this substitution in order for your recipe to rise.