This document describes methods to calibrate the performance of the optical components of bio-fluorescent airborne particle counter (BFAPC), which is used to count microbiological particles suspended in a known volume of air. Measurement principle of BFAPC is a single particle measurement of light scattering and/or laser-induced fluorescence. The size range of particles measured by BFAPC typically ranges from 0.5 m to 10 m in particle diameter.