A typical 1/4 cup serving of rice flour contains 2.4 grams of protein (5.95 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 7% of the calories in rice 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, rice flour ranks 98th by protein per serving, and 627th out of all 796 foods on the site. Set against corn flakes, another grain entry in the database, a serving carries about 0.5 g more protein (corn flakes has 1.9 g per 1 cup).
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 39.5 g. The per-100 g figure lets you compare it directly against any other food here, whatever its serving.
Source: USDA FoodData Central #169714 - "Rice flour, white, unenriched" (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
Rice flour protein FAQ
How much protein is in rice flour per 100 g?
Rice flour has 5.95 g of protein per 100 g. A typical 1/4 cup serving (39.5 g) provides 2.4 g.
Is rice flour a complete protein?
No. Rice 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 rice flour cover?
A 1/4 cup serving of rice flour contains 2.4 g of protein, about 5% of the 50 g reference Daily Value.
Is rice flour a good source of protein?
Rice flour is only a minor source of protein, and about 7% of its calories come from protein, which makes it more of an energy food than a protein food. Set against corn flakes, another grain entry in the database, a serving carries about 0.5 g more protein (corn flakes has 1.9 g per 1 cup).