Data analysis for chemical protective clothing permeation testing involves a number of equations and experimental factors. Experimenter bias and possible calculation errors are critical issues when determining permeation parameters, including various breakthrough times, steady-state permeation rate, cumulative permeation, etc.. Permeation Calculator, a Microsoft Windows compatible program is a computer tool for automating the permeation testing data analysis. It works for either a closed-loop or an open-loop permeation test. The program imports the data file collected during a permeation test and calculates all the permeation parameters related to ASTM F 739 and ISO 6529 standards based on a series of algorithms, strategies, and decision making. Upon completion, the program displays all the permeation parameters together with relevant information and the permeation curve as a report file. Permeation Calculator is intended to help industrial hygienists avoid labor intensive hand calculations of the permeation parameters. The program will also prevent experimenter bias thus ensuring identical results will be obtained from a given data file.