Red blood cell count optimal range and reference range
Compiled by Alina Radu, founder of Sera, from the published sources below · Last reviewed November 9, 2026
Sera's bands for Red blood cell count, which differ for men and women:
- Male: Optimal 4.8 – 5.5 ×10⁶/μL (4.8 – 5.5 ×10¹²/L); sufficient 4.3 – 5.9 ×10⁶/μL (4.3 – 5.9 ×10¹²/L); out of range below 4.3 or above 5.9 ×10⁶/μL.
- Female: Optimal 4.2 – 4.8 ×10⁶/μL (4.2 – 4.8 ×10¹²/L); sufficient 3.9 – 5.4 ×10⁶/μL (3.9 – 5.4 ×10¹²/L); out of range below 3.9 or above 5.4 ×10⁶/μL.
Evidence grade: Published reference interval. A band that primarily reflects a published adult laboratory or population reference interval. It is not necessarily applicable to every assay or laboratory.
At Sera's last range review a change to this band was proposed and held, because the evidence for it was thin, so the band is unchanged. The note below says where it matches published intervals and where it does not.
All units
| Unit | Applies to | Optimal | Sufficient | Out of range |
|---|---|---|---|---|
| ×10⁶/μL | Male | 4.8 – 5.5 | 4.3 – 5.9 | below 4.3 or above 5.9 |
| ×10⁶/μL | Female | 4.2 – 4.8 | 3.9 – 5.4 | below 3.9 or above 5.4 |
| ×10¹²/L | Male | 4.8 – 5.5 | 4.3 – 5.9 | below 4.3 or above 5.9 |
| ×10¹²/L | Female | 4.2 – 4.8 | 3.9 – 5.4 | below 3.9 or above 5.4 |
| millions/μL | Male | 4.8 – 5.5 | 4.3 – 5.9 | below 4.3 or above 5.9 |
| millions/μL | Female | 4.2 – 4.8 | 3.9 – 5.4 | below 3.9 or above 5.4 |
| M/μL | Male | 4.8 – 5.5 | 4.3 – 5.9 | below 4.3 or above 5.9 |
| M/μL | Female | 4.2 – 4.8 | 3.9 – 5.4 | below 3.9 or above 5.4 |
| x E12/L | Male | 4.8 – 5.5 | 4.3 – 5.9 | below 4.3 or above 5.9 |
| x E12/L | Female | 4.2 – 4.8 | 3.9 – 5.4 | below 3.9 or above 5.4 |
| /mm³ | Male | 4,800,000 – 5,500,000 | 4,300,000 – 5,900,000 | below 4,300,000 or above 5,900,000 |
| /mm³ | Female | 4,200,000 – 4,800,000 | 3,900,000 – 5,400,000 | below 3,900,000 or above 5,400,000 |
What the evidence says
The acceptable bands sit within 0.1 of published adult intervals, which differ a little between laboratories: MedlinePlus gives 4.2 to 5.7 for men and 3.8 to 5.1 for women on one page and 4.6 to 6.2 and 4.2 to 5.4 on another. Only the women's upper edge of 5.4 matches a source exactly. The optimal bands are functional targets with no published source.
Sources
- RBC count — U.S. National Library of Medicine (MedlinePlus Medical Encyclopedia), 2026 · Government / public-health guidanceNormal red cell count is 4.2 to 5.7 million cells per microlitre in men and 3.8 to 5.1 in women (reviewed February 2026). Sera's lower edges of 4.3 and 3.9 are each 0.1 above these.
- CBC blood test — U.S. National Library of Medicine (MedlinePlus Medical Encyclopedia), 2024 · Government / public-health guidanceA second MedlinePlus page gives 4.6 to 6.2 million cells per microlitre for men and 4.2 to 5.4 for women. The women's upper limit of 5.4 is Sera's number.
- Haematology reference ranges — Gloucestershire Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceAdult red cell count 4.50 to 6.50 ×10¹²/L in men and 3.80 to 5.80 in women. Supports 3.8 as the women's lower limit.
- Full Blood Count (Haematology) — Liverpool Clinical Laboratories, Royal Liverpool University Hospital (NHS), 2013 · Laboratory / reference-interval sourceRed cell count 4.4 to 6.0 ×10¹²/L in men and 4.2 to 5.4 in women. Supports 6.0 as a men's upper limit and 5.4 as the women's. The page is undated; it is the laboratory's current page and says these ranges replaced the ones used before 2 April 2013.
What RBC # (Red Blood Cell Count) measures
The total number of red blood cells in your blood.
Low RBC points to anemia. Important for checking how well your blood carries oxygen.
Related blood cell health markers
- Hemoglobin (HGB)
- Hematocrit (HCT)
- Mean Corpuscular Volume (MCV)
- Mean Corpuscular Hemoglobin (MCH)
- Mean Corpuscular Hemoglobin Concentration (MCHC)
- RDW (Red Cell Distribution Width)
- WBC # (White Blood Cell Count)
- Neutrophils #
- Lymphocytes #
- Monocytes #
- Eosinophils #
- Basophils #
- Neutrophils %
- Lymphocytes %
- Monocytes %
- Eosinophils %
- Basophils %
- Immature Granulocytes %
- Platelets (Thrombocytes)
- PCT (Plateletcrit)
- Reticulocytes (Absolute)
- Reticulocytes (%)
- Ferritin
- Iron (Serum)
- Transferrin
- TIBC (Total Iron Binding Capacity)
- Transferrin Saturation
- UIBC (Unsaturated Iron Binding Capacity)
See Red blood cell count in the full list of biomarker ranges