Score any protein, in seconds.

A protein quality score rates how efficiently your body can digest and use a protein based on its essential amino acid profile and digestibility, not just the grams on the label. It matters because two foods with the same protein content can differ in how much your body actually absorbs and uses for muscle and tissue repair.

Protein quality is measured with lab methods like PDCAAS and DIAAS that compare a food's essential amino acids against an FAO reference pattern, then adjust for digestibility (bioavailability), or how much your body actually absorbs. This calculator turns those ideas into a single 0 to 10 Protein Quality Score by weighing efficiency, purity, value, and the bioavailability of the protein source you select.

A DIAAS of 1.0 (100%) or higher means the protein supplies all essential amino acids in fully digestible amounts and is considered high quality; above 0.75 is good. PDCAAS is capped at 1.0, so any score of 1.0 is treated as complete. On this calculator's 0 to 10 scale, scores above 7.0 indicate high quality and above 8.5 reflect premium, highly efficient protein sources.

PDCAAS (Protein Digestibility Corrected Amino Acid Score) uses fecal digestibility and is truncated at a maximum of 1.0, so it cannot show that a protein exceeds requirements. DIAAS (Digestible Indispensable Amino Acid Score) is the newer FAO-recommended method that measures each amino acid's digestibility in the small intestine and is not capped, so it ranks high-quality proteins more accurately. DIAAS values above 1.0 are common for whey and other animal proteins.

Whey protein is one of the highest quality proteins, with a DIAAS around 1.09 and a PDCAAS of 1.0, thanks to excellent digestibility and a high leucine content. Other top-ranked sources include whey and casein from milk, eggs, and lean animal meats. The highest quality protein sources are generally animal-based because they supply all essential amino acids in digestible amounts.

Most single plant proteins score lower than animal proteins because they are limited in one essential amino acid, but soy is a complete protein with a PDCAAS of 1.0 and a DIAAS near 0.90, the highest of common plant sources. Quinoa, buckwheat, and pea-rice blends are also complete. Combining or blending plant proteins (for example pea plus rice) covers each one's limiting amino acid and can match animal protein quality.

The limiting amino acid is the essential amino acid present in the smallest amount relative to your needs, which caps how much of that protein your body can use. In most grains the limiting amino acid is lysine, while in legumes and beans it is usually methionine. Pairing grains with legumes offsets each one's limiting amino acid, which is why rice and beans together form a higher-quality protein.

A complete protein contains all nine essential amino acids in adequate amounts, while an incomplete protein is low in at least one. Animal proteins, soy, quinoa, and buckwheat are complete; most grains, nuts, and legumes are incomplete on their own. Eating a variety of plant proteins across the day provides all essential amino acids even from incomplete sources.

Leucine is the essential amino acid that triggers muscle protein synthesis, so proteins rich in it support muscle growth and repair more effectively. Whey is especially high in leucine, which is one reason it scores so well for quality. Reaching roughly 2.5 to 3 grams of leucine per serving is often cited as the threshold for maximizing the muscle-building response.

Lean proteins with high efficiency and purity, such as whey isolate, egg white, and clean plant blends, support satiety while keeping calories lower. Use the score breakdown to spot fillers, low absorption, or poor value so you can compare products objectively for your goals.

Yes. The calculator works for protein powders, shakes, ready-to-drink products, bars, and whole foods like chicken, eggs, and tofu, as well as non-dairy and lactose-free sources such as plant powders, soy, legumes, and nuts. Enter the nutrition facts per serving from the label or a nutrition database and select the matching protein source type (for example Egg White for eggs or Soy for tofu) to get an accurate bioavailability score.

Save calculation stores up to 8 entries in your browser only. Add to Compare pins up to 3 items side by side so you can see the score and breakdown for each product at a glance. Both lists are private to this device and persist between visits.

There is a common myth that the body can only handle a limited amount of protein at once. In reality your digestive system absorbs nearly all the protein you eat. What is capped is muscle protein synthesis: research suggests roughly 20 to 40 grams of high-quality protein per meal is enough to maximize it for most adults. Protein beyond that is still used, just for other jobs, including tissue repair, hormone and enzyme production, and energy when needed.

Protein digestion begins in the stomach, where hydrochloric acid unfolds protein molecules and the enzyme pepsin starts breaking them into smaller peptides. It continues in the small intestine, where pancreatic enzymes such as trypsin and chymotrypsin break those peptides down further, and additional enzymes convert them into individual amino acids that pass into the bloodstream. Those amino acids are what your body uses for muscle growth, tissue repair, and enzyme and hormone production.