India VIX is a volatility index based on the index option prices of NIFTY and is computed using the best bid and ask quotes of the out-of-the-money near and mid-month NIFTY option contracts.
- The index depicts the expected market volatility over the next 30 calendar days expressed in annualized terms.
If you are interested to know about the formula and the way it is computed, Check the below links by NSE
https://static.nseindia.com//s3fs-public/inline-files/white_paper_IndiaVIX.pdf
https://static.nseindia.com//s3fs-public/inline-files/India_VIX_comp_meth.pdf
As Nifty and Sensex almost perform inline, there won’t be much of difference in the number. But, yeah, ideally, we should also have VIX for Sensex by BSE