What is a normal red blood cell count?
About 4.5 to 6.0 for men and 3.8 to 5.3 for women. That’s one NHS lab. Others differ, so a woman’s 5.6 is high at one NHS lab and in range at another.
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What is a normal red blood cell count?
For adults at the North Bristol NHS lab, it’s 4.5 to 6.0 for men and 3.8 to 5.3 for women. Gloucestershire’s NHS lab goes higher, up to 6.5 for men and 5.8 for women.
The unit, x10¹²/L, means million million red cells in each litre of blood. So 4.5 is four and a half million million.
| Lab | Men (x10¹²/L) | Women (x10¹²/L) |
|---|---|---|
| North Bristol NHS | 4.5 to 6.0 | 3.8 to 5.3 |
| Gloucestershire NHS | 4.50 to 6.50 | 3.80 to 5.80 |
Sources: Severn Pathology (North Bristol NHS); Gloucestershire Hospitals NHS
The bottom of the range is the same at both labs. The top is where they part.
Your next move: find the range printed beside your own result and compare against that.
Why is my lab’s RBC range different?
Labs often use different testing methods, so they set different ranges. Each range comes from testing large groups of healthy people.
Take a woman with a count of 5.6. At North Bristol it sits above 5.3, so it’s flagged high. At Gloucestershire it sits under 5.8, so it’s in range.
That’s why the range printed beside your result is the one that counts. You can’t compare it with a range you find somewhere else, this page included.
One result is a photo, not a film, so a repeat test can show whether a number stays out of range. Healthy people sometimes land outside the range. And a result inside it doesn’t always mean you’re well.
Before you talk to anyone about your result
- Find the range printed beside your red cell count.
- Note your haemoglobin, haematocrit and MCV lines from the same sheet.
- Write down any symptoms, such as tiredness, shortness of breath, headaches or dizziness.
- Use the same lab for repeat tests if you can, so results compare fairly.
- Ask to talk to a healthcare professional if you don’t understand your results.
Sources: MedlinePlus; NHS: blood tests
Reading results in the NHS App? See how to read NHS App blood test results.
Normal RBC count by age for children
A child’s range moves a lot in the first year. At North Bristol, a count of 4.5 is in range for a 1-year-old but above the range for a 3-month-old.
| Age | Red cell count (x10¹²/L) |
|---|---|
| Birth | 3.7 to 6.5 |
| 2 weeks | 3.9 to 5.9 |
| 4 weeks | 3.2 to 5.9 |
| 2 to 6 months | 3.1 to 4.3 |
| 6 months to 1 year | 4.1 to 5.3 |
| 1 to 6 years | 3.9 to 5.3 |
| 6 to 12 years | 4.0 to 5.2 |
| 12 to 18 years, girls | 4.1 to 5.1 |
| 12 to 18 years, boys | 4.5 to 5.3 |
Adult ranges at both labs are split by sex, not by age.
For your child, use the range on their own report and ask the doctor who ordered the test.
What does an RBC blood test show?
It counts your red blood cells. They carry an iron-rich protein called haemoglobin, which takes oxygen from your lungs to every cell in your body.
The count is almost always part of a full blood count (FBC). You don’t need to do anything to prepare for it.
| Line | What it is | Adult range at one NHS lab |
|---|---|---|
| Haemoglobin (Hb) | The oxygen-carrying protein inside red cells. | Men 130 to 180 g/L. Women 115 to 165 g/L. |
| Haematocrit (HCT) | How much of your blood is red cells. 0.40 means 40%. | Men 0.40 to 0.54. Women 0.37 to 0.47. |
| MCV (mean cell volume) | How big your red cells are on average. | 80 to 100 fL (femtolitres, a tiny unit of size) for adults. |
Sources: Gloucestershire Hospitals NHS; MedlinePlus
MCV helps explain a low count. It tends to be low with iron deficiency, long-lasting inflammation or thalassaemia (an inherited blood condition), and high with B12 or folate deficiency. More in our guides to haemoglobin levels by age and the MCV blood test.
What if my RBC count is low or high?
Your doctor will look at your symptoms, your history and your other blood test results. A count on its own rarely gives the answer.
| Count | Some possible causes | Symptoms it may bring |
|---|---|---|
| Low | Anaemia, blood loss, pregnancy, kidney failure or alcohol use disorder. | Tiredness, weakness, shortness of breath, headache, dizziness, pale skin or an uneven heartbeat. |
| High | Dehydration, lung disease, sleep apnoea (breathing that stops and starts in sleep), misused anabolic steroids or living high up. | Headache, dizziness or problems with your vision. |
Sources: MedlinePlus; NWL Pathology (NHS)
A high count doesn’t always mean extra red cells. Short of fluid? Your count can read high after dehydration, because the same cells sit in less liquid.
Next tests may include iron, B vitamins and a reticulocyte count, which checks how many young red cells your bone marrow is making.
For causes and next steps, see low red blood cell count and high red blood cell count.
When to speak to a GP
Some surgeries only contact you if they need to discuss results. Speak to a GP if:
- You think you might have iron deficiency anaemia: tiredness and lack of energy, shortness of breath, noticeable heartbeats, paler skin than usual or headaches.
- You have lasting symptoms of too many red cells, such as headaches, blurred vision, red skin, tiredness, high blood pressure, dizziness, tummy discomfort, confusion, nosebleeds, bruising, gout or itchy skin after a bath or shower.
- You look pale or feel tired all the time. Or you have unexplained bruising, bleeding, fever, swollen glands, tiny red or purple spots on the skin, or infections that keep coming back. NICE tells doctors to consider a very urgent full blood count for adults with these.
- Your results confuse you. The NHS says to ask to talk to a healthcare professional.
The NHS lists signs of a blood clot for people with too many red cells. Get medical help straight away for any of these:
- pain, swelling, redness and tenderness in one leg
- a heavy ache or warm skin in that area
- breathlessness, chest or upper back pain, or coughing up blood
- feeling lightheaded or dizzy, or fainting
Too many red cells also raise the risk of heart attack and stroke. Get emergency help if you think someone is having one.