1 Platelet count measures the number of platelets in a volume of blood and usually ranges between 150,000 to 400,000 per cmm. 2  Mean platelet volume (MPV) measures the average size of platelets in a volume of blood.3  The normal range is between 6 to 12 femtoliters (a very small fraction of a liter). RBC (red blood cell) count measures the number of red blood cells in a volume of blood and usually ranges between 4.2 to 5.9 million cells per cmm.