Mean Corpuscular Hemoglobin Calculator

How it is calculated

MCH is the average amount of hemoglobin in one red blood cell. The tool uses MCH (pg) = Hgb (g/dL) × 10 ÷ RBC, where Hgb is the hemoglobin concentration in grams per decilitre and RBC is the red cell count in 10¹² per litre (the same as millions per microlitre). The answer is in picograms with two decimals. The class uses fixed cut-offs: below 27 pg is Hypochromic, 27 to 31 inclusive is Normochromic and above 31 is Hyperchromic, from the reference value of 29 ± 2 pg in Clinical Methods (chapter 152). Laboratories may use slightly different ranges, so check the one printed on your report. Both inputs must be above zero, and the tool rejects values that point to a wrong unit: hemoglobin above 30 g/dL or an RBC above 20 gives no result. The calculated MCH itself must also fall between 10 and 60 pg; a value outside that range is physiologically impossible and is not shown. It is an educational index only and, unlike MCV, says nothing about cell size.

Common mistakes

• Entering hemoglobin in g/L (140) instead of g/dL (14). The tool shows no result because 140 is far outside the allowed range, so convert first.
• Entering the RBC count as cells per microlitre (4,800,000). That also gives no result; use the 10¹²/L or millions form (4.8).
• Confusing MCH with MCHC. MCH is hemoglobin per cell in pg, while MCHC is hemoglobin per volume of red cells in g/dL, so the cut-offs are different.
• Reading Hypochromic or Hyperchromic as a diagnosis. They describe one number, and doctors read MCH together with MCV, MCHC and the clinical picture.
• Assuming that any result shown is right. A pair giving an MCH outside 10 to 60 pg (hemoglobin 14 with RBC 1.0, which would be 140 pg) is rejected, but a mistyped RBC of 3.0 instead of 4.8 still passes and prints 46.67 pg, so compare your values against the lab report.