What is 9.00am cst in IST?

9:00 am CST is equal to 8:30:00pm the previous evening in India Standard Time. CST is UTC - 6:00, and IST is UTC+5:30.You first subtract 6 hours fom 9 am, and get 3 am. Then you subract 5-1/2 hours from 3 am, so you get 9:00 pm.