Manual Cell Count (Hemocytometer Method)

• The unit of volume is  cubic millimeter (mm³ ) .
• 1 mm³  =  1.00003 µL 
• RBC  = conventional =  x 10⁶/µL  SI x 10¹²/L
• WBC = conventional =  x 10³/µL  SI x 10⁹/L
• Plt = conventional =  x 10³/µL  SI x 10⁹/L

Neubauer Hemocytometer

• 1 large square == 1 mm
• 1 central square is divided into 25 smaller squares so 1 sm square == 1/25 mm or a volume of 1/25 x 1/10 == 1/250 µL
• depth == 0.1 mm == 1/10 mm
• count == (cells/#largesquare) x dilution factor x depth

• count == (cell/#largesquare) x dilution factor x 10

• example : cells counted = 100 in 4, dilution = 1:200                                                                                             100/4 x 200 x 10 = 50000/mm = 50  x 10³/µL

SOURCE: Henry’s Clinical Diagnosis and Management by Laboratory Methods 21 ed

ch 29 p 461-462