Blood Cell Index Calculator (MCV, MCH, MCHC)
Work out the average red blood cell size, haemoglobin content and haemoglobin concentration from a blood count.
What it does
A full blood count tells you how many red cells there are, how much haemoglobin they carry and how much of the blood they fill. Those three numbers are not separate facts. Put them together and they describe the average red blood cell: how big it is, how much haemoglobin it holds and how concentrated that haemoglobin is. Those are the red cell indices, and they are the quickest way to see what kind of anaemia a person has.
The clinical reference behind this page explains that the indices were first introduced by Wintrobe in 1929 to define the size and haemoglobin content of red cells, and that they can be calculated as soon as the haemoglobin, the haematocrit and the red cell count are known. Modern laboratory counters work them out automatically, and they form part of every blood count report.
Each index answers a different question. The mean cell volume says how large the cells are on average, in femtolitres. The mean cell haemoglobin says how much haemoglobin the average cell carries, in picograms. The mean cell haemoglobin concentration says how packed that haemoglobin is inside the cell, in grams per decilitre.
This page takes the three values from a blood count and returns the three indices, plus a plain reading of whether the cells are small, normal or large, and whether they are pale, normal or dark. The reference ranges shown come from the MedlinePlus blood count article, which also lists the usual adult ranges for the red cell count, the haematocrit and the haemoglobin itself.
The limits are real. These are estimates for information only, they depend on the laboratory that ran the count, and a blood count is read next to the symptoms, the history and the rest of the blood tests by a clinician. Nothing on this page should be used to work out a diagnosis or a treatment.
How to use
- Take the haemoglobin from your blood count report, in grams per decilitre.
- Take the haematocrit, the percentage of the blood made up of cells.
- Take the red blood cell count, in millions of cells per microlitre.
- Read the mean cell volume. Below the reference range the cells are small, above it they are large.
- Read the mean cell haemoglobin and the mean cell haemoglobin concentration, which say how much haemoglobin the cells carry and how concentrated it is.
- Take the reading to your clinician, who will set it against your symptoms, your history and the rest of your blood tests.
Formula
- MCV
- Mean cell volume, the average size of one red blood cell, in femtolitres.
- MCH
- Mean cell haemoglobin, the average amount of haemoglobin in one red blood cell, in picograms.
- MCHC
- Mean cell haemoglobin concentration, the haemoglobin packed into the cells, in grams per decilitre.
- Haematocrit
- The share of the blood volume that is red cells, in percent.
- Red cell count
- The number of red cells in millions per microlitre.
The factor of 10 in the first two formulas puts the numbers into the right scale: the haematocrit in percent and the cell count in millions per microlitre give a volume in femtolitres, and the haemoglobin in grams per decilitre with the same count gives a mass in picograms. The reference values quoted in the clinical source are 87 plus or minus 7 fL for MCV, 29 plus or minus 2 pg for MCH and 34 plus or minus 2 g per dL for MCHC, with an average normal red cell distribution width of 13 plus or minus 1.5 percent.
Worked example
Example: a blood count of 10.5 g per dL, 32 % and 4.3 million
Defaults: haemoglobin 10.5 g per dL, haematocrit 32 % and a red cell count of 4.3 million per microlitre.
- MCV is the haematocrit in percent times 10 over the cell count: 32 x 10 / 4.3 = 74.42 fL.
- MCH is the haemoglobin times 10 over the cell count: 10.5 x 10 / 4.3 = 24.42 pg.
- MCHC is the haemoglobin times 100 over the haematocrit: 10.5 x 100 / 32 = 32.81 g per dL.
- The mean cell volume of 74.42 fL sits under the reference range of 80 to 100 fL, so the cells are small, which the tool calls microcytic.
- The mean cell haemoglobin of 24.42 pg sits under the range of 27 to 32 pg, so the cells are pale, which the tool calls hypochromic.
- The mean cell haemoglobin concentration of 32.81 g per dL is inside the range of 32 to 36 g per dL.
- The tool shows 74.42 fL, 24.42 pg, 32.81 g per dL, small cells (microcytic) and light cells (hypochromic).
Reference table
| Index | How it is calculated | Usual adult range | What it describes |
|---|---|---|---|
| MCV | Haematocrit in % x 10 divided by the red cell count | 80 to 100 fL | the average size of a red cell |
| MCH | Haemoglobin x 10 divided by the red cell count | 27 to 32 pg | the average haemoglobin in one cell |
| MCHC | Haemoglobin x 100 divided by the haematocrit in % | 32 to 36 g per dL | how concentrated the haemoglobin is |
| Red cell count | measured directly by the counter | 4.6 to 6.2 million per microlitre for men | how many cells there are |
| Haematocrit | measured directly by the counter | 40 to 55 % for men, 36 to 48 % for women | the share of blood that is cells |
Limits
- The reference ranges vary a little between laboratories, so a result near the edge of a range may not mean the same thing in every lab.
- Blood counts change with altitude, with hydration and during an illness, so the same person can produce different numbers on different days.
- The indices are calculated, not measured, so a lab that counts cells badly produces indices that are wrong in the same way.
- None of this is a diagnosis. Anaemia has several causes and the pattern of the indices is only one part of the picture a clinician works from.
Common mistakes
- Using the haematocrit as a fraction instead of a percentage. The factor of 10 in the MCV formula assumes the percentage is written out in full.
- Using the haemoglobin in mmol per litre instead of grams per decilitre, which is how some laboratories report it.
- Reading a low MCV as a low haemoglobin. The two say different things: MCV is about cell size and haemoglobin is about the total in the blood.
- Forgetting the red cell count. Without it, only the MCHC can be worked out.
- Comparing your numbers with a range for a different group. The reference ranges differ for men, women, children and pregnancy.
Try it yourself
Quick checks. Answers sit tucked under each question.
What are the indices for a count of 15 g per dL, 45 % and 4.8 million?
An MCV of 93.75 fL, an MCH of 31.25 pg and an MCHC of 33.33 g per dL. All three sit inside the usual adult ranges, so the tool describes the cells as normal in size and normal in haemoglobin content.
A count of 9.2 g per dL, 28 % and 3.4 million gives which pattern?
An MCV of 82.35 fL, an MCH of 27.06 pg and an MCHC of 32.86 g per dL, so the cells are of normal size with a normal haemoglobin content even though the haemoglobin itself is low. That combination points a clinician towards blood loss or a problem with production rather than small pale cells.
How is the mean cell volume worked out?
Take the haematocrit in percent, multiply it by 10 and divide by the red cell count in millions per microlitre. For 32 % and 4.3 million that is 320 / 4.3 = 74.42 fL, which is the average volume of one red blood cell.
Questions
What do MCV, MCH and MCHC stand for?
Mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration. They are also called the red cell indices, and they were introduced by Wintrobe in 1929.
What is a normal MCV?
MedlinePlus quotes 80 to 100 femtolitres for adults in its blood count article, and a slightly different 79 to 95 in its red blood cell indices article, which shows how the range depends on the source and the laboratory.
What does a low MCV mean on its own?
That the red cells are smaller than usual. The clinical reference lists the common causes as low iron, lead poisoning and thalassaemia, and a clinician reads that list alongside the rest of the count.
What is the difference between MCH and MCHC?
MCH is the average mass of haemoglobin in one cell, while MCHC is the concentration of haemoglobin inside the cells. MCHC divides the haemoglobin by the cell volume, so it does not care how many cells there are.
Do I need the red cell count as well?
Yes. The count is needed for the MCV and the MCH, and the haematocrit and the haemoglobin are needed for the MCHC. With all three measurements the three indices follow directly.
Does altitude change these numbers?
It can. The MedlinePlus blood count article notes that blood counts may vary with altitude, because the body makes more red cells at height to carry oxygen to the tissues.
Sources
- MedlinePlus medical encyclopedia: red blood cell indices, with the calculation methods
- MedlinePlus laboratory test: red blood cell indices, with the meaning of each index
- NCBI Clinical Methods: red cell indices, with the reference values