The protein content of flour varies depending on the type and brand. The following flours are categorized based on their protein content.

Cake & Pastry Flour: 7 – 9 % protein
All-Purpose Flour: 10 – 12% protein
Bread Flour: 12 – 16% protein
Whole-Wheat Flour: 16% protein

To determine the exact protein content of flour, look at the nutritional information on the package. For example, if the nutritional information displays 12 grams of protein per 100 grams of flour, the protein content is 12%.

However, if the nutritional information is displayed in something other than “per 100” grams, you need to do some math.
If there is 4 grams of protein per 30 grams of flour, you need to multiply 4 by the number 100 and then divide by 30 (see example below).

4 g protein per 30 g flour
4 × 100 = 400
400 / 30 = 13.33

This flour has a protein content of 13.33%.

Use this formula to determine the percentage of protein in flour:

(x) grams of protein per (y) grams of flour
(x) x 100 = (z)
(z) / (y) = % of protein content in the flour