Blood
Red Blood Cells (RBC)
Also known as: Erythrocytes, RCC, Red Cell Count
CONVERT & COMPARE
×10⁶/µL
=
5
×10¹²/L
Reference ranges by source
Published adult intervals: 12, from 6 named sources, shown in ×10⁶/µL.
SOURCE
SEX
AGE
RANGE
VISUAL
CITE
J
JSCC / JAMT Japan
Male
≥18y
4.35 – 5.55 ×10⁶/µL
J
JSCC / JAMT Japan
Female
≥18y
3.86 – 4.92 ×10⁶/µL
T
Turkey Nationwide Reference Intervals
Male
≥18y
4.43 – 6.07 ×10⁶/µL
T
Turkey Nationwide Reference Intervals
Female
≥18y
3.96 – 5.31 ×10⁶/µL
J
JSCC / JAMT Japan
Male · ≥18y
4.35 – 5.55 ×10⁶/µL
J
JSCC / JAMT Japan
Female · ≥18y
3.86 – 4.92 ×10⁶/µL
T
Turkey Nationwide Reference Intervals
Male · ≥18y
4.43 – 6.07 ×10⁶/µL
T
Turkey Nationwide Reference Intervals
Female · ≥18y
3.96 – 5.31 ×10⁶/µL
Ages 0–17 (CALIPER)
5 age- and sex-stratified entries from the Canadian Laboratory Initiative on Pediatric Reference Intervals.
SOURCE
SEX
AGE
RANGE
VISUAL
CITE
About Red Blood Cells (RBC)
A red blood cell (RBC) count measures the number of red blood cells, also known as erythrocytes, in your blood. Red blood cells are made in your bone marrow, the spongy tissue inside your large bones. They contain hemoglobin, an iron-rich protein that carries oxygen from your lungs to every cell in your body. Your cells need oxygen to grow, reproduce, and make energy for you to function. An RBC count that is higher or lower than normal is often the first sign of an illness. So, the test may allow you to get treatment even before you have symptoms.
You may get this test as part of a CBC, which is often included in a routine checkup. You may also need this test if you are getting treatment that might affect your blood cell counts, such as chemotherapy, to monitor health conditions, such as chronic kidney disease, or if you have symptoms of a low or high red blood cell count.
Main source: MedlinePlus ↗
Useful for
A red blood cell (RBC) count is almost always part of a complete blood count (CBC), a group of tests that measures the number and type of cells in your blood.
The RBC measurement is used to help diagnose red blood cell disorders, such as anemia, a condition in which your body does not make enough healthy red blood cells.
Main source: MedlinePlus ↗
Interpretation
Your results will show whether you have a normal red blood cell count or a count that is too low or too high.
A low RBC count is called anemia. Common causes include iron, vitamin B12, or folate deficiency, blood loss, kidney disease, long-term illness, bone marrow problems, and certain inherited blood disorders such as thalassemia or sickle cell disease.
A high RBC count is called erythrocytosis or polycythemia. Causes include lung or heart conditions that lower oxygen, smoking, dehydration (which makes the count look high), living at a high altitude, sleep apnea, and a bone marrow condition called polycythemia vera. Misuse of certain drugs for athletic performance (such as anabolic steroids or erythropoietin) can also raise the count.
Talk with your provider to find out what may be causing an abnormal result. RBC is usually looked at along with hemoglobin, hematocrit, and other CBC values to make sense of the result.
For general wellness information only. Talk to a clinician about your specific results.
Main source: MedlinePlus ↗
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Related biomarkers
More tests in the blood category.
Sources
M
Mayo Clinic Laboratories
L
Labcorp
N
Nordic Reference Interval Project
U
UK Pathology Harmony
J
JSCC / JAMT Japan
T
Turkey Nationwide Reference Intervals
C
CALIPER: Canadian Pediatric Reference Intervals
Last updated 2026-05-02
This page presents source-specific reference data and sourced explanations. For general wellness information only. This is not medical advice. For diagnosis or treatment of any condition, talk to a qualified clinician.