In general, use the following equation to calculate CSF cell count:

• (total cells counted x dilution) / (number of squares counted x volume of 1 square) = cells per microliter.

For an undiluted specimen in which 10 squares are counted:

• (total cells counted x 1) / (10 squares counted x 0.1 mm³ per square) = cells per microliter.

Therefore, in this example:

• (total cells counted) / (1 mm³) = cells per microliter.

1 mm³ is equal to 1 microliter.