**4. Dimensions of RBC**

Photomicrographs are used to measure the dimensions of RBC's. Average values for the mean cellular volume in normal subjects are from approximately 85 to 91 fl. Ninety-five percent of normal red cells are between about 60 and 120 fl in volume. Various results have yielded an average normal value for red cell diameter of 7.2 to 7.4 microns.
