the study of air infiltration into the buildings is important from several perspectives that may be noted to energy and design of hvac systems, indoor air quality and thermal comfort and design of smoke control systems. given the importance of this issue, an experimental and numerical study of air infiltration through conventional doors and windows has been explored in iran. to this end, at first cracks around the conventional doors and windows in iran have been identified and their dimensions were measured. then the effect of crack dimensions on air infiltration was investigated and in order to predict the air infiltration rate through doors and windows, two common equations (power law and quadratic) was fitted to our obtained experimental data and compared based on the coefficient of determination with each other. the acquired results indicate that the air infiltration rate per unit width of the crack is constant and the depth of the cracks has negligible impact on the air infiltration rate. but the effect of the height of cracks is significant and with respect to depth and width of crack has greater effect on the air infiltration rate. power law equation compared to quadratic one is able to predict the experimental data more properly. also in order to predict air infiltration rate through doors and windows the constant coefficients of power law equation for cracks with conventional dimensions was obtained.