Mensa has an online “workout” quiz that will sort of determine whether you’re likely to qualify for membership. I thought it was interesting, so I took it, and I made 20/30 with 28 questions answered in the timeframe given. According to the test, this means I have “a good chance,” which probably means I’d score a couple of questions below the minimum and be laughed at. I took an IQ test in high school and wouldn’t have qualified then.
You can take the test here. The time limit is 30 minutes, but it isn’t imposed unless you want it to be.
For those not familiar with Mensa, it is an organization whose only membership requirements are that you score above 98% of the general population in a qualified IQ or Mensa test.