This paper reports a simplified Broekhoff equation for calculating the pore size distribution from adsorption isotherms. The equation is as follows. Where For desorption branch of adsorption isotherms For adsorption branch of adsorption isotherms The results obtained from this equation agree with data from the Broekhoff equation calculated by a computer. The pore size distribution from the authors equation for adsorption branch agrees with that of the desorption branch. Due to this approximation simplified equation a minicomputer may be interfaced to a measuring instrument in use. The application range of the simplified equation is 10 A- 300A.