You need to score 132 or equivalent to on some Mensa test or any approved IQ test. Since various tests have different norms and IQ that is culturally different rating so the Mensa has chosen to side with all the concept of percentile. You have to wind up in the top 2% of the IQ test takers to join Mensa as a member.
What is Mensa?
The word ‘MENSA’ means mind, dining table or month in Latin. Generally, the term is culturally considered equivalent to a table or a table that is round having people of higher intelligence sit by ignoring their racial, national and cultural backgrounds.
All of the online IQ tests are perhaps not considered suited to the measurement of your intelligence. Though, in my opinion, the line that is off tests are also not 100% dependable but they will have at least some requirements, time frame, administrative set-up and supervision.