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Crude Protein Calculator

Convert a Kjeldahl or Dumas nitrogen percent into crude protein with a chosen N-to-protein factor.

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Crude protein (%)

About this calculator

Use this calculator in a feed or food lab when you have %N from Kjeldahl or Dumas and need crude protein for a label or ration sheet.

Protein % = %N × factor. 6.25 is the generic factor; dairy often uses 6.38, wheat 5.70. This is nitrogen times a convention, not a true protein assay, and it does not distinguish non-protein nitrogen.

Nitrogen (%): Nitrogen as a percent of the sample, for example 2.8 from the Kjeldahl result.

N-to-protein factor: Default 6.25; milk 6.38; wheat flour often 5.70.

Crude protein (%): Estimated crude protein percent of the sample.