Hey there
Generally CGPA conversion is different for different Boards but for 8.73 cgpa you are in top 20 percentile and your jee mains percentile is also good wait for september results you have chances of getting into NITs, IIITs.
check the link
https://engineering.careers360.com/articles/jee-main-eligibility-criteria#:~:text=JEE%20Main%20Eligibility%20Criteria%202020%20for%20Droppers&text=For%20NITs%2C%20IIITs%20and%20CFTIs,minimum%20of%2065%25%20marks%20required.
good luck
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