Chemistry

Instant, private, and free

Crude Protein Calculator.

Estimate crude protein from measured nitrogen percentage and a material-specific conversion factor.

On-device calculationNo signup
01

Set your values

Results update as you type.

Crude protein: 15.63 %

Crude protein

15.63%

How to Use

Crude protein (%) = nitrogen (%) × the conversion factor you provide; no material factor is assumed.

Use a named source for any material-specific coefficient. This page does not infer local rates, species tables, laboratory methods, or safety guidance.

Use Cases

Feed formulation

Quickly estimate protein content in animal feed ingredients to balance rations and meet nutritional requirements.

Example: Enter nitrogen % of soybean meal (7.5%) with factor 6.25 to get crude protein ≈ 46.9%.

Food quality control

Monitor protein levels in food products during development or production to ensure consistency and meet specifications.

Example: Check crude protein in milk powder using factor 6.38.

Frequently Asked Questions

How is crude protein calculated from nitrogen?
Crude protein is estimated by multiplying the nitrogen percentage by a nitrogen-to-protein factor. The default factor is 6.25, but you can adjust it based on the material being analyzed (e.g., 5.70 for wheat, 6.38 for dairy products).
What nitrogen-to-protein factor should I use?
The factor depends on the material. Common values include 6.25 for general foods and feeds, 5.70 for wheat and most cereals, 6.38 for dairy products, and 5.30 for nuts. Use a material-specific factor for more accurate results.
Is this calculator suitable for regulatory or legal purposes?
No, this calculator provides estimates for educational and reference purposes. For regulatory compliance or official labeling, always use validated laboratory methods and consult relevant standards.

Tips & Common Mistakes

Tips

  • Use the correct nitrogen-to-protein factor for your material to improve accuracy.
  • Ensure your nitrogen percentage is measured by a reliable method (e.g., Kjeldahl or Dumas).
  • For mixed materials, consider using a weighted average factor if applicable.
  • Remember that this is an estimate; actual protein may vary due to non-protein nitrogen.

Common Mistakes to Avoid

  • Using the default factor 6.25 for all materials, even when a specific factor is known.
  • Entering nitrogen as a decimal instead of a percentage (e.g., 0.02 instead of 2%).
  • Ignoring the presence of non-protein nitrogen, which can overestimate true protein content.

Last updated: August 13, 2026