π©Έ RBC Indices Calculator
MCV, MCH, MCHC from your CBC, interpreted.
For informational purposes only, not medical advice. Consult a healthcare professional.
Red cell indices turn three CBC numbers into a diagnostic pattern. MCV is the average red cell size, MCH the average hemoglobin per cell, and MCHC the hemoglobin concentration within cells. Small cells (MCV under 80) suggest iron deficiency or thalassemia; normal-sized cells with anemia suggest chronic disease or blood loss; large cells (over 100) suggest B12 or folate deficiency. This calculator computes the indices and interprets the pattern for study and discussion with your clinician.
How to Use This Calculator
Enter hemoglobin, hematocrit, and RBC count from the CBC; RDW is optional but sharpens the interpretation. The calculator derives the three indices and names the pattern.
Copy hemoglobin in g/dL, hematocrit in percent, and RBC count in millions per microliter exactly as the lab reports them.
Add RDW if reported. A high RDW with low MCV points toward iron deficiency; a normal RDW with low MCV points toward thalassemia trait.
Read the pattern: microcytic, normocytic, or macrocytic, with the usual differential for each.
How the Math Works
MCV equals hematocrit times 10 divided by RBC count in millions: 30 times 10 divided by 4.0 is 75 fL. MCH equals hemoglobin times 10 divided by RBC: 10 times 10 divided by 4.0 is 25 pg. MCHC equals hemoglobin times 100 divided by hematocrit: 10 times 100 divided by 30 is 33.3 g/dL. Reference bands: MCV 80 to 100 fL, MCH 27 to 33 pg, MCHC 32 to 36 g/dL, RDW 11.5 to 14.5 percent. Pattern logic: low MCV is microcytic, normal MCV normocytic, high MCV macrocytic; low MCHC is hypochromic; high RDW means varied cell sizes.
Worked Example
A CBC with hemoglobin 10, hematocrit 30, and RBC 4.0 gives an MCV of 75.0 fL (80-100), MCH of 25.0 pg (27-33), and MCHC of 33.3 g/dL (32-36). The calculator calls this Microcytic normochromic anemia pattern: small, pale cells. With the RDW elevated at 15.5, the pattern favors favors iron deficiency (high RDW), since iron deficiency produces varied small cells while thalassemia trait typically keeps RDW normal.
Reading Your Result
Microcytic anemia splits by RDW: high RDW suggests iron deficiency, normal RDW suggests thalassemia trait, and the Mentzer index (MCV divided by RBC) above 13 favors iron deficiency while under 13 favors thalassemia. Normocytic anemia points to chronic disease, kidney disease, acute blood loss, or marrow problems. Macrocytic anemia points to B12 or folate deficiency, alcohol effect, liver disease, or medications; true megaloblastic anemia usually shows hypersegmented neutrophils on the smear. The indices narrow the field; iron studies, B12, and reticulocyte count finish the job.
| Pattern | MCV | Usual suspects |
|---|---|---|
| Microcytic | Under 80 | Iron deficiency, thalassemia |
| Normocytic | 80-100 | Chronic disease, blood loss |
| Macrocytic | Over 100 | B12/folate deficiency |
Limitations
Indices describe, they do not diagnose: iron studies, B12, folate, and reticulocyte count confirm. Mixed deficiencies can normalize the MCV and hide in plain sight. Reference ranges vary slightly by lab and by age, and newborns have physiologically high MCV. Anemia workup belongs with a clinician, especially with symptoms like fatigue, pallor, or shortness of breath.
Related Calculators
Related tools: reticulocyte count calculator pediatric transfusion calculator BMI calculator.
For informational purposes only, not medical advice. Consult a healthcare professional.
Frequently Asked Questions
What are RBC indices?
Computed values describing red blood cells: MCV (average cell size), MCH (average hemoglobin per cell), MCHC (hemoglobin concentration in cells), and RDW (size variation). They are calculated from the CBC hemoglobin, hematocrit, and RBC count, and they pattern-match anemias.
What is a normal MCV?
80 to 100 femtoliters in adults. Under 80 is microcytic, over 100 macrocytic. Newborns run higher physiologically. The MCV is the single most useful index for sorting anemia causes.
What causes microcytic anemia?
Iron deficiency first, thalassemia trait second, then anemia of chronic disease and sideroblastic causes. RDW helps split iron deficiency (high RDW) from thalassemia trait (normal RDW). Iron studies confirm.
What causes macrocytic anemia?
B12 or folate deficiency, excess alcohol, liver disease, hypothyroidism, and drugs like methotrexate. Megaloblastic forms show hypersegmented neutrophils. B12 deficiency can cause irreversible nerve damage, so it should not wait.
What is MCHC?
Mean corpuscular hemoglobin concentration: hemoglobin per unit of red cell volume, normally 32 to 36 g/dL. Low values mean hypochromic (pale) cells, classic in iron deficiency. Truly high MCHC is rare and often a lab artifact from hemolysis or lipemia.
What does high RDW mean?
Red cell distribution width measures size variation; high means anisocytosis, cells of many sizes. It rises early in iron deficiency and in mixed deficiencies. A normal RDW with microcytosis favors thalassemia trait.
What is the Mentzer index?
MCV divided by RBC count: above 13 suggests iron deficiency, below 13 thalassemia trait. It is a screening heuristic, not a diagnosis. Hemoglobin electrophoresis confirms thalassemia.
Can you be anemic with normal indices?
Yes. Early iron deficiency, combined B12 and iron deficiency, and anemia of chronic disease can all present normocytic. Normal indices never rule out anemia; the hemoglobin itself defines it.
Do athletes have different indices?
Endurance athletes often show slightly low hemoglobin from plasma volume expansion, so-called sports anemia, with typically normal indices. True iron deficiency is also common in endurance athletes, especially menstruating women, and needs checking.
When does anemia need urgent care?
With chest pain, shortness of breath at rest, fainting, very low hemoglobin, or signs of active bleeding. Gradual mild anemia is worked up routinely; symptomatic or severe anemia is urgent. Do not watch and wait with red-flag symptoms.