Protein from nitrogen calculator

Nitrogen to protein on the right factor, and two protein offers compared on the same footing.

FAO factors
Offer comparison
Dry basis
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Protein

Inputs used

Method, factors and sources

What this does not do. It does not tell you which factor your label must use: for labelling and claims the factor is set by the rules for your product and market. It assumes the nitrogen figure is total nitrogen, measured by Kjeldahl or a similar method.

Method

Protein = total nitrogen x conversion factor. The general factor, 6.25, assumes proteins contain about 16% nitrogen.
Material factors are the Jones factors in Table 2.1 of the FAO report, the same ones listed in our article.
Comparing offers: each protein figure is divided by the factor its supplier used to recover nitrogen, then multiplied by the common factor you choose.
Dry basis = as-is result x 100 / (100 - moisture).

Sources

FAO, Food energy: methods of analysis and conversion factors, FAO Food and Nutrition Paper 77, 2003, Chapter 2. fao.org. Accessed 17 September 2026.
Mariotti F, Tomé D and Mirand PP, "Converting nitrogen into protein: beyond 6.25 and Jones' factors", Critical Reviews in Food Science and Nutrition, 2008. doi.org/10.1080/10408390701279749.
Codex Alimentarius, Standard for Whey Powders, CXS 289-1995. fao.org. Accessed 15 September 2026.
SpecSol technical team, "Why a protein figure depends on a conversion factor", SpecSol Ingredients, 2026. specsol.in/articles/protein-content-nitrogen-conversion-factor.html.

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Produced with the protein from nitrogen calculator at specsol.in. Arithmetic on the values entered; factors from FAO (2003). SpecSol Ingredients LLP, Mumbai.

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