The mean corpuscular volume, or mean cell volume, is a proportion of the normal volume of a red blood corpuscle. The measure is accomplished by duplicating a volume of blood by the extent of blood that is cell, and separating that item by the quantity of erythrocytes in that volume. MCV stands for mean corpuscular volume. There are three main types of corpuscles (blood cells) in your blood–red blood cells, white blood cells, and platelets. An MCV blood test measures the average size of your red blood cells, also known as erythrocytes. Red blood cells move oxygen from your lungs to every cell in your body. Your cells need oxygen to grow, reproduce, and stay healthy. If your red blood cells are too small or too large, it could be a sign of a blood disorder such as anemia, a vitamin deficiency, or other medical condition.