1Ī hematocrit reading of 50% (which is within the hematocrit normal range) means that 50% of the total blood volume is red blood cells.Ĭhecking for normal hematocrit levels is one of the RBC indices that can help doctors diagnose many health conditions. Doctors can then measure the proportion of red blood cells at the bottom. Another way to check Hct levels is to put blood in a test tube and centrifuge it. Shiel on MedicineNet says that hematocrit levels can be calculated using the average volume of red blood cells and determining the amount of hemoglobin.