Full Blood Count (FBC) Blood Test: What It Checks and What It Costs in the UK
A full blood count, usually shortened to FBC, is one of the most commonly requested blood tests in the UK. It checks the cells in your blood and can give a clinician useful clues about anaemia, infection, inflammation and some blood disorders.
It is a broad test, though. An FBC cannot explain every symptom on its own, and a result outside the lab’s reference range does not automatically mean something is wrong. Your age, symptoms, medicines and medical history all matter.
What does a full blood count test measure?
An FBC examines several parts of your blood. The exact report varies slightly between laboratories, but you will normally see haemoglobin (Hb), the oxygen-carrying protein that drops in anaemia; the red blood cell count itself; mean cell volume (MCV), which shows whether your red cells are smaller or larger than usual; and mean cell haemoglobin (MCH), the average amount of haemoglobin per cell. The report also covers white cells, which fight infection, along with a breakdown of the different white cell types such as neutrophils and lymphocytes, and platelets, the fragments involved in clotting.
The NHS describes an FBC as a test for blood conditions such as iron deficiency anaemia. Hospital pathology services also use it as a first-line test when investigating symptoms or monitoring a known condition.
Why might you need an FBC?
A GP may request an FBC if you have ongoing tiredness, breathlessness, pale skin, frequent infections, unexplained bruising or heavy periods. It also gets used before some treatments and to monitor conditions that affect blood cells.
Low haemoglobin can point towards anaemia, but the FBC cannot tell you the cause by itself. Iron deficiency is the commonest reason, yet blood loss, long-term inflammation, vitamin deficiencies and inherited conditions can all be involved. Depending on the pattern, a clinician might follow up with ferritin, vitamin B12, folate, kidney or thyroid tests. I have seen people fixate on a single number from their report and miss the point entirely: these results only mean something together, and against your own history.
A high white cell count often goes with infection or inflammation. A low count has plenty of explanations too, including medicines and viral illness. Platelets can move up or down for many reasons. This is why comparing your report with a friend’s gets you nowhere.
What happens during the test?
The lab needs a small blood sample, usually taken from a vein in your arm. Some private providers offer an FBC with a home finger-prick kit instead, but read the collection instructions before ordering. A sample that is too small, clotted or delayed in the post may need repeating, which costs you another week.
For a clinic appointment the draw itself takes a few minutes. You generally do not need to fast for an FBC alone, although you might if the same visit includes cholesterol or glucose tests. Follow whatever the provider tells you rather than assuming.
Private results usually arrive within a few working days, sometimes with reference ranges and a written clinician review. Those ranges are a guide, not a diagnosis. A result can sit inside the normal range while you still feel unwell, or drift slightly outside without anything being wrong.
How much does a private FBC cost?
Prices change, so check the product page before buying. At the time of writing, these are the FBC tests listed in our comparison data:
| Provider | Test | Price | Link |
|---|---|---|---|
| Medichecks | Full Blood Count (FBC) Blood Test | £59 | View test |
| Goodbody Clinic | Full Blood Count Blood Test | £69 | View test |
| Vitall | Full Blood Count (FBC) Test Kit | £79 | View test |
Collection fees can change the total. Some providers include a home finger-prick kit but charge extra for a clinic venous draw or a nurse home visit. When comparing prices, check whether the amount includes postage, sample collection and any clinician review.
You can compare full blood count and anaemia tests side by side. An anaemia panel may include ferritin or other markers that an FBC alone does not measure, so the cheapest option is not always the closest match for your question.
Can an FBC diagnose iron deficiency?
An FBC can show a pattern that fits iron deficiency anaemia. Low haemoglobin, MCV and MCH would lead most clinicians to investigate iron status next. But the FBC does not measure stored iron directly.
That is what ferritin is for, though inflammation and some illnesses complicate how ferritin should be read. If you have heavy periods, persistent fatigue, restless legs, hair shedding or breathlessness, ask a healthcare professional whether ferritin and other tests make sense for you. Do not start high-dose iron simply because your FBC looks unusual. Too much iron harms you, and the underlying cause still needs finding.
What if your result is abnormal?
Read the laboratory or provider comments first, then book a GP appointment if the report recommends follow-up or your symptoms continue. Take the complete report with you, including the reference ranges. A clinician may repeat the FBC, request extra tests or examine you depending on what they find.
Seek urgent medical help for severe breathlessness, chest pain, fainting, heavy bleeding, confusion or a rapidly worsening condition. A private test supports medical care rather than replacing it. If you are pregnant, receiving cancer treatment, taking medicines that affect blood counts or managing a long-term condition, stay with the healthcare team already involved in your care.
An FBC gives a quick overview of the blood cells, and that is genuinely useful, but it is one piece of the picture. Choose the test around your symptoms and the decision you need to make, and get clinical advice when a result is unclear.
Sources
- NHS: Blood tests
- North West London Pathology: Full blood count
- Leeds Teaching Hospitals: Full blood count
Prices checked against provider listings on 22 August 2026 and may change.
Header image: Jess Loiterton / Pexels
Disclaimer
This guide is for general information only. It is not medical advice, a diagnosis or a substitute for an appointment with a qualified healthcare professional. Always discuss concerning symptoms or test results with your GP or another clinician.