A paper published in The Lancet estimates that when you include people who never seek medical attention and never get diagnosed, there is an infection fatality rate of 0.65%, with a lower bound estimate being 0.38% and and upper bound being 1.33%.
https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30243-7/fulltextGiven the current confirmed death totals according to
https://www.worldometers.info/coronavirus/ there are 55,737 deaths worldwide. That would mean around 8.6 million people are infected globally, with a lower estimate being 4.2 million, and an upper bound being at most 14.7 million.
That's just with confirmed deaths though. The real numbers are likely lower than those estimates, but probably not by much.
