How much extasy do you take to overdose?

It's believed to be between 8,5 and 25,5 grams for an 80kg adult. That's about the amount in 60 to 190 XTC pills of decent quality.

Important note: that is OD'ing on just MDMA! That doesn't mean nothing else goes wrong when taking high doses of MDMA. Depending on the person even 1 pill can be dangerous in terms of, for one, overheating.