A　grid　is　a　geographically　distributed　resource　sharing　environment　across　multiple　organizations.　The　most　typical　grid　resources　are　clusters　with　high　performance/cost　ratio.　In　general,　these　clusters　are　shared　as　non-dedicated　grid　resources　since　local　users　may　run　their　jobs　simultaneously.　Local　jobs　are　usually　queued　and　processed　in　a　batch　mode　with　uncertain　waiting　time,　while　grid　jobs　always　require　advance　reservations　with　guaranteed　resource　allocation.　In　this　paper,　we　provide　quantitative　analysis　on　the　impact　of　advance　reservations　over　queued　jobs,　in　terms　of　job　waiting　time　and　resource　utilization,　respectively.　It　is　observed　that　advance　reservations　will　lead　to　longer　job　waiting　time　and　lower　resource　utilization.　That　is　to　say,　advance　reservations　should　cost　more　than　queued　jobs.　In　this　work,　based　on　quantitative　experimental　results,　an　empirical　formula　for　cost　estimation　of　advance　reservations　over　queued　jobs　is　presented.　It　is　suggested　that　compared　with　queued　jobs,　advance　reservations　should　be　doubly　charged　to　compensate　resource　utilization　loss.　If　the　notice　time　of　an　advance　reservation　is　short　below　a　threshold,　additional　cost　should　be　applied　further　since　queue　waiting　time　is　increased.　©　2010　World　Scientific　Publishing　Company.