You cannot directly determine an IFSC code from only an account number
Check the bank passbook or cheque book
Log in to the bank’s net banking or mobile banking app
Contact the bank branch where the account is held
Call the bank’s customer care
Use the bank’s official website branch locator
Check any bank statement or account opening documents
Ask the account holder for the IFSC code
Use the RBI or bank branch details if you know the branch name and location