How are MCV, MCH, and MCHC calculated?

MCV equals haematocrit percent divided by red cell count, times ten. MCH equals haemoglobin divided by red cell count, times ten. MCHC equals haemoglobin divided by haematocrit percent, times one hundred. All three are derived from the three CBC values you enter.

What is the difference between MCH and MCHC?

MCH is the average mass of haemoglobin per red cell, measured in picograms. MCHC is the concentration of haemoglobin within the cell volume, measured in g/dL. MCH scales with cell size, while MCHC reflects how densely each cell is packed with haemoglobin.

How does MCV classify anaemia?

MCV below 80 femtolitres is microcytic, pointing to iron deficiency or thalassaemia. MCV between 80 and 100 is normocytic, seen in acute blood loss or chronic disease. MCV above 100 is macrocytic, suggesting B12 or folate deficiency, alcohol, or liver disease.

What does a high MCHC mean?

A genuinely high MCHC is unusual because there is a ceiling to how much haemoglobin fits in a cell. It most often signals hereditary spherocytosis or a laboratory artefact such as cold agglutinins, lipaemia, or a measurement error, so it warrants a check rather than a diagnosis.

Do these indices replace a blood film?

No. The indices give averages that narrow the differential quickly, but they hide mixed populations. A blood film, reticulocyte count, and iron or vitamin studies are still needed to confirm the cause. Reference ranges also vary by laboratory, age, and sex.

What is the Red Cell Indices (MCV, MCH, MCHC) Calculator?

Calculate MCV, MCH, and MCHC from haemoglobin, haematocrit, and red cell count, then classify anaemia as microcytic, normocytic, or macrocytic with a differential-diagnosis prompt. For haematology and primary care. It runs free in your browser on Gera Tools, with nothing uploaded.

Red Cell Indices (MCV, MCH, MCHC) Calculator

Name: Red Cell Indices (MCV, MCH, MCHC) Calculator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

The red cell indices turn three routine numbers from a full blood count into a description of the red cells themselves: how big they are and how much haemoglobin they carry. That description is the fastest way to narrow the cause of an anaemia, which is why MCV, MCH, and MCHC appear on every CBC report.

How it works

All three indices are simple ratios of the measured haemoglobin, haematocrit, and red cell count:

MCV  (fL)   = (Hct% / RBC) x 10
MCH  (pg)   = (Hb / RBC) x 10
MCHC (g/dL) = (Hb / Hct%) x 100

MCV is the average volume of a single red cell, MCH is the average mass of haemoglobin it carries, and MCHC is the concentration of haemoglobin packed into that volume. The haematocrit is entered as a percentage and the red cell count in units of 10 to the 12 per litre.

Classifying anaemia: the three-way split

MCV drives the classic morphological classification:

Microcytic anaemia (MCV under 80 fL). Small red cells most commonly result from iron deficiency — the most prevalent anaemia worldwide — where inadequate iron limits haemoglobin synthesis and cells fail to reach full size. Thalassaemia trait produces a similar picture but with a normal or elevated red cell count and a characteristic low MCH. Anaemia of chronic disease can present in either the microcytic or normocytic band. The Mentzer index (MCV divided by red cell count) provides a quick screen to separate iron deficiency (typically greater than 13) from thalassaemia trait (typically less than 13), though confirmation requires iron studies and haemoglobin electrophoresis.

Normocytic anaemia (MCV 80–100 fL). Cells are normal size but reduced in number. Causes include acute haemorrhage (before the haematocrit has equilibrated), haemolytic anaemias, renal failure driving reduced erythropoietin, and early combined deficiencies. The normocytic band is often the most diagnostically challenging because it covers a wide range of mechanisms.

Macrocytic anaemia (MCV over 100 fL). Large cells most often arise from deficiency of vitamin B12 or folate, both of which are required for normal DNA synthesis during red cell maturation. Other causes include alcohol, hypothyroidism, liver disease, and myelodysplastic syndrome. A megaloblastic blood film and hypersegmented neutrophils support the B12/folate diagnosis.

MCHC as a second axis

MCHC adds information MCV alone cannot provide. A low MCHC (under 32 g/dL) indicates hypochromic cells — less haemoglobin packed in, which in combination with microcytosis is strongly suggestive of iron deficiency. A high MCHC above the normal ceiling is physiologically unusual because cells cannot exceed a concentration limit; when reported high, hereditary spherocytosis or a laboratory artefact (cold agglutinins, lipaemia, or erroneous automated counting) should be considered before accepting the value as real.

Worked example

For a patient with Hb 9.0 g/dL, Hct 29%, and RBC 4.8 × 10¹²/L:

MCV  = (29 / 4.8) × 10 = 60.4 fL    →  microcytic
MCH  = (9.0 / 4.8) × 10 = 18.8 pg   →  low
MCHC = (9.0 / 29) × 100 = 31.0 g/dL →  borderline hypochromic

This pattern — microcytic, low MCH, borderline MCHC — is characteristic of iron deficiency anaemia. The next step would be serum ferritin and iron studies to confirm.

Limits of indices alone

These indices are averages and can hide a mixed red cell population, so they narrow the differential but do not close it. A blood film, reticulocyte count, and iron and vitamin studies remain essential, and reference ranges vary by laboratory, age, and sex. The RDW (red cell distribution width) complements MCV by flagging whether the population is heterogeneous — a normal MCV with a high RDW suggests a mixed population of small and large cells that average out to normal.