A typical 1/4 cup serving of sorghum flour contains 2.6 grams of protein (8.43 g per 100 g), which makes it only a minor source of protein. That covers roughly 5% of the 50 g reference Daily Value, so it adds toward your protein total for the day.
Only about 9% of the calories in sorghum flour come from protein, so it is more of an energy food than a protein food. It is worth eating for other reasons; the protein it adds to a day is incidental.
Among the 111 grains in the database, sorghum flour ranks 95th by protein per serving, and 619th out of all 796 foods on the site. Set against oat bran bread, another grain entry in the database, a serving carries about 0.5 g less protein (oat bran bread has 3.1 g per 1 slice).
It is an incomplete protein on its own; pairing it with other plant foods across the day covers the full range of essential amino acids. The serving above is measured by volume at 30.3 g. The per-100 g figure lets you compare it directly against any other food here, whatever its serving.
Source: USDA FoodData Central #168943 - "Sorghum flour, whole-grain" (SR Legacy, published 4/1/2019). Values are the published reference figures for that record, not lab measurements for a specific brand or batch.
Quick answers
Sorghum flour protein FAQ
How much protein is in sorghum flour per 100 g?
Sorghum flour has 8.43 g of protein per 100 g. A typical 1/4 cup serving (30.3 g) provides 2.6 g.
Is sorghum flour a complete protein?
No. Sorghum flour is an incomplete protein on its own; pairing it with other protein sources across the day covers the full range of essential amino acids.
How much of the Daily Value does a serving of sorghum flour cover?
A 1/4 cup serving of sorghum flour contains 2.6 g of protein, about 5% of the 50 g reference Daily Value.
Is sorghum flour a good source of protein?
Sorghum flour is only a minor source of protein, and about 9% of its calories come from protein, which makes it more of an energy food than a protein food. Set against oat bran bread, another grain entry in the database, a serving carries about 0.5 g less protein (oat bran bread has 3.1 g per 1 slice).