Blood cells

White blood cells help your body fight infection. They are part of your immune system.

The main types of white blood cell are:

• neutrophils, eosinophils and basophils (all called granulocytes)
• lymphocytes (there are B lymphocytes and T lymphocytes)
• monocytes.

Your red blood cells carry oxygen from your lungs to all the cells in your body. Inside your red blood cells there is a protein called haemoglobin which helps carry the oxygen.

Platelets help your blood to clot. They stick together to stop bleeding if you have a cut or a bruise.

All your blood cells start off as stem cells, which are made in the bone marrow (a soft material inside your bones).

Blood stem cells can divide and multiply in the bone marrow to produce many other blood cells. The diagram below shows how blood stem cells can grow into any of the blood cells that are needed, including white blood cells, red blood cells and platelets.

Your bone marrow makes a huge number of blood cells every second. If everything’s working normally, your body makes the right number of each type of cell to keep you healthy.

However, if something goes wrong with this process, you may get blood cells not developing properly or multiplying too quickly. These abnormal cells are not detected by the body’s natural defence system, meaning that they continue to multiply and develop into blood cancer.

A full blood count is a blood test that checks the number of red blood cells, white blood cells and platelets in your blood.

Everyone has slightly different numbers of each type of blood cell. If you’re healthy, the amount normally stays the same, with only slight changes over time.

Below is an idea of the normal ranges for blood cells in an average healthy adult. It’s important to know that the range of what is ‘normal’ or ‘healthy’ for you may not be the same as these numbers. If you have blood cancer, or have had blood cancer in the past, your own blood counts are likely to be different.

The numbers might look complicated, but your hospital team should be able to explain what each one means in a simple way. They will also be able to tell you what the expected ranges are for you personally. Blood count results can differ slightly between hospitals due to the machines involved, so don’t be alarmed if your results change if you have a test in another location. Always check with your main hospital if you have any concerns or questions.

• Haemoglobin (Hb) level - 135-175 g/l (men), 120-155 g/l (women)
• Platelets - 150-400 x 10⁹/l
• White blood cells (WBC) - 4.0-11.0 x 10⁹/l
• Neutrophils - 2.0-7.5 x 10⁹/l
• Lymphocytes - 1.5-4.5 x 10⁹/l

We have developed a chart you can use to track your own blood test results. It also has space to write down the results of other tests you may have, and any notes or questions you have for your hospital team.

Open the PDF and print it at home as many times as you like, or call us if you don’t have a printer and we can send a copy to you by post.

Whilst talking about your blood cells and test results, your doctor or clinical nurse specialist (CNS) might use some medical terms you’re not familiar with. You may also see these words on your NHS app or in a letter.

Read our glossary below to find out what they mean, and don’t be afraid to ask for an explanation if you don’t understand anything you’re told.

Last full review April 2026. Next full review due April 2029. We may make factual updates to the information between reviews.

We would like to thank Consultant Haematologist Dr Priya Sriskandarajah for checking the clinical accuracy of this information.