A typical 1 cup cubes serving of star fruit contains 1.4 grams of protein (1.04 g per 100 g), which makes it only a minor source of protein. That covers roughly 3% of the 50 g reference Daily Value, so it adds toward your protein total for the day.
Around 13% of the calories in star fruit come from protein, so it is more of an energy food than a protein food. It contributes to a day's protein total, but the bulk of what it delivers is energy rather than amino acids - treat it as a contributor alongside a denser source, not as the protein in a meal.
Among the 71 fruits in the database, star fruit ranks 25th by protein per serving, and 697th out of all 796 foods on the site. Set against plantain, another fruit entry in the database, a serving carries about 0.5 g less protein (plantain has 1.9 g per 1 cup sliced raw).
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 132 g. The per-100 g figure lets you compare it directly against any other food here, whatever its serving.
Source: USDA FoodData Central #171715 - "Carambola, (starfruit), raw" (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
Star fruit protein FAQ
How much protein is in star fruit per 100 g?
Star fruit has 1.04 g of protein per 100 g. A typical 1 cup cubes serving (132 g) provides 1.4 g.
Is star fruit a complete protein?
No. Star fruit 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 star fruit cover?
A 1 cup cubes serving of star fruit contains 1.4 g of protein, about 3% of the 50 g reference Daily Value.
Is star fruit a good source of protein?
Star fruit is only a minor source of protein, and about 13% of its calories come from protein, which makes it more of an energy food than a protein food. Set against plantain, another fruit entry in the database, a serving carries about 0.5 g less protein (plantain has 1.9 g per 1 cup sliced raw).