i believe this thread belongs to the 'india-based airlines' forum....
you may calculate the allowance & excess charges here:
https://www.jetairways.com/EN/IN/Tra...llowances.aspx
9w sets baggage allowance based on the type of ticket you buy....typically their excess baggage charges are around inr 300 per kg....if you log onto the 'manage booking' page with you pnr then you have the option of purchasing excess baggage at a discounted rate....