The usability evaluation of a web site has been found using quantitative metrics. A case study has been used to collect quantitative data from participants to determine and measure 3 main factors of web site usability; effectiveness, efficiency, and satisfaction. A questionnaire has been delivered to 32 participants and they were asked to complete 8 tasks which have been determined to navigate the web site. The results of the study produced an enriched perspective to measure the web site usability. We measured the effectiveness, efficient, and satisfaction with quantitative data and explored the weakness of each factor.