A normal blood platelet count is 150,000 to 400,000 platelets per microliter, says the National Institutes of Health. Platelets are components of the blood that assist with blood clotting, and the normal range may vary slightly depending on the individual.
A platelet count can be useful as a method of ascertaining the cause of unusual levels of bleeding or clotting. Doctors may also use it to monitor or diagnose diseases. A low platelet count is below 150,000, while a high platelet count is 400,000 or above, states the National Institutes of Health. Individuals with a low platelet count may experience excessive bleeding, while individuals with a high platelet count may be at risk of blood clot formations.