A typical 1/4 cup serving of potato flour contains 2.8 grams of protein (6.9 g per 100 g), which makes it only a minor source of protein. That covers roughly 6% of the 50 g reference Daily Value, so it adds toward your protein total for the day.
Only about 8% of the calories in potato 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, potato flour ranks 86th by protein per serving, and 602nd out of all 796 foods on the site. Set against oatmeal bread, another grain entry in the database, a serving carries about 0.5 g more protein (oatmeal bread has 2.3 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 40 g. The per-100 g figure lets you compare it directly against any other food here, whatever its serving.
Source: USDA FoodData Central #168446 - "Potato flour" (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
Potato flour protein FAQ
How much protein is in potato flour per 100 g?
Potato flour has 6.9 g of protein per 100 g. A typical 1/4 cup serving (40 g) provides 2.8 g.
Is potato flour a complete protein?
No. Potato 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 potato flour cover?
A 1/4 cup serving of potato flour contains 2.8 g of protein, about 6% of the 50 g reference Daily Value.
Is potato flour a good source of protein?
Potato flour is only a minor source of protein, and about 8% of its calories come from protein, which makes it more of an energy food than a protein food. Set against oatmeal bread, another grain entry in the database, a serving carries about 0.5 g more protein (oatmeal bread has 2.3 g per 1 slice).