Dial *121# from your Airtel number and check the SMS balance option in the menu
Open the Airtel Thanks app and view your SMS balance in the account details
Send an SMS to Airtel customer care if your circle supports balance inquiry by message
Call Airtel customer care at 121 and ask for your SMS balance
Check your plan details in the Airtel app or website to see the included SMS quota
Use the USSD balance menu available on your Airtel SIM if shown by your network circle