Some time we need to calculate number of days between two dates in crm, we can easily do this using below JS script var d1=crmForm.all.FirstDate.DataValue; var d2=crmForm.all.SecondDate.DataValue; var DayValue=1000*60*60*24; alert(Math.ceil((d2.getTime()-d1.getTime())/DayValue)); Update for Dynamics 365 var d1=Xrm.Page.getAttribute(“FirstDate”).getValue(); var d2=Xrm.Page.getAttribute(“SecondDate”).getValue(); var DayValue=1000*60*60*24; alert(Math.ceil((d2.getTime()-d1.getTime())/DayValue));