I am using XBEE-PRO-S2b rf module.
Kindly tell me how can i calculate the time period taken by Tx frame of 60 bytes to reach its corresponding co-ordinator.
The battery life calculator located at http://knowledge.digi.com/articles/Knowledge_Base_Article/Low-power-operation-for-telephone-modem-interface-board-PKG-T/?q=PKG-T&l=en_US&fs=Search&pn=1 will help you to know the actual on air time but it will not tell you how long the rout discovery process and any additional hops needed to get the data there will take. That is something you will really need to test and I would suggest doing it to the loop back cluster ID and End point. This way you can measure the round trip time and cut it in half to the one way time.
You can also go to http://knowledge.digi.com/articles/Knowledge_Base_Article/Timing-Comparison-For-Data-Transfer-By-Product/?q=timing&l=en_US&fs=Search&pn=1 to get an idea of how long it takes to get 1 byte and 32 bytes transmitted over one hop.