Depends on the version. But generally, way too long for its own good. Over the years it's been given so much needless padding, just to make it longer, that the show itself feels rather lost inside all the extra repeats, reprises, extended arrangements, prologues upon prologues, and the like.
If I remember correctly, JOSEPH runs about 80 minutes including an intermission. That overblown '90's version of the show that not only included the megamix at the end, but had many of the songs sung twice within the context of the show probably ran a bit longer than 90 minutes.
