The Red Blood Cell Distribution Width (RDW) Calculator is to measure of the variation of red blood cell (RBC) width that is reported as part of a standard complete blood count. Usually red blood cells are a standard size of about 6-8祄. Certain disorders, however, cause a significant variation in cell size. Higher RDW values indicate greater variation in size. Normal reference range in human red blood cells is 11 - 14%. If anemia is observed, RDW test results are often used together with mean corpuscular volume (MCV) results to figure out what the cause of the anemia might be.
RDW = (Std Dev of MCV*100/MCV)