Understanding the Complete Blood Count (CBC)

One important test your doctor will ask you to get is a complete blood count, or CBC for short. The CBC measures the number of each blood cell type in your blood sample. Below are the types of information the CBC measures.

  • Red blood cell count (RBC) measures the actual number of red blood cells in a given volume of blood. A low count is called anemia.
  • White blood cell count (WBC) measures the actual number of white blood cells in a given volume of blood. A low count can mean you have an increased risk of getting an infection.
  • White blood cell differential (dif) looks at the types of white blood cells in your blood. There are many different types of white blood cells. Each of them protects you from different types of infections.
  • Hemoglobin (Hgb) measures the amount of this oxygen-carrying protein in red blood cells. This level is low in people with anemia.
  • Hematocrit (Hct) measures how much of a given volume of whole blood is made up of red blood cells. In healthy men, 41 percent to 50 percent of blood is red blood cells. In healthy women, 35 percent to 46 percent is red blood cells. This number is about 3 times the hemoglobin.
  • Platelet count measures the number of platelets in a given volume of blood. A low count means you have an increased risk of bleeding if you get cut or injured.
  • Mean Corpuscular Volume (MCV) measures the average size of red blood cells. It is high when red blood cells are larger than normal. It is low when red blood cells are smaller than normal.

Test

Adult Normal Range*
(Varies in different clinics or hospitals, or in different part of the U.S.)

Red blood cell count (varies with how high up you are in the mountains)

Men 4.7 to 6.1 million cells per microliter (cells/mcL)
Women 4.2 to 5.4 million cells/mcL

White blood cell count

4,500 to 10,000 (4.5 to 10) thousand cells/mcL

Hemoglobin

Male 13.8 to 17.2 grams/dL
Female 12.0 to 15.6 grams/dL 

Hematocrit

Male 40.7% - 50.3%
Female 36.1% - 44.3%

Platelets

150 to 450 thousand/mcL

MCV (Mean corpuscular volume)

80 to 100 femtoliter

*Normal blood values involve a range rather than a single volume.

Note:

  • cells/mcL = cells per microliter
  • gm/dL = grams per deciliter
  • pg/cell = picograms per cell