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Complete Blood Count (CBC)

Red Blood Cell Count (RBC)

Normal range 4.2–5.9 10⁶/µL (4.2–5.9 10¹²/L SI). Specimen: Whole blood (EDTA).

Also known as: erythrocyte count.

4.2–5.9 10⁶/µLReference range

Reference range

Conventional10⁶/µL
4.25.9
SI10¹²/L
4.25.9
SpecimenWhole blood (EDTA)
Conventional range4.2–5.9 10⁶/µL
SI range4.2–5.9 10¹²/L
Conversion factor×1 (conventional → SI)
PanelComplete Blood Count (CBC)

Convert any Red Blood Cell Count (RBC) result between units on the unit converter.

What is the normal range for Red Blood Cell Count (RBC)?

The standard teaching reference range for Red Blood Cell Count (RBC) is 4.2–5.9 10⁶/µL in conventional units, or 4.2–5.9 10¹²/L in SI units. This value is measured in whole blood (edta).

Source: Adult reference values compiled from Pagana & Pagana, Mosby's Diagnostic and Laboratory Test Reference, and Fischbach & Dunning, A Manual of Laboratory and Diagnostic Tests. Reference ranges vary by laboratory, method, age, sex, and population — always use the range printed on the actual result.

Above the range

Common causes of a high Red Blood Cell Count (RBC)

  • Polycythemia vera
  • Chronic hypoxia (COPD, high altitude)
  • Dehydration (relative rise)
  • Erythropoietin excess

Below the range

Common causes of a low Red Blood Cell Count (RBC)

  • Anemia of any cause
  • Acute or chronic blood loss
  • Hemolysis
  • Bone marrow failure

At the bedside

Nursing considerations

  • Men run higher than women; use sex-specific ranges when reported.
  • Interpret alongside hemoglobin, hematocrit, and the RBC indices.

Typical ranges: men ~4.7–6.1 and women ~4.2–5.4 × 10¹²/L.

Study aid

Your notes on Red Blood Cell Count (RBC)

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