I don't know the capacity, but I have a book that lists the area and volume of several famous churches throughout the world. Unfortunately, that book is locked away in storage at the moment...

more importantly, how long would it take the niagara falls to fill it?

If you're doing a compairson of church sizes, make sure to note it was originally built as a mosque, which doesn't have the same type of 'seating' needs as a church.

Actually, it was originally built as a church and then later converted to a mosque. I don't think it ever had fixed seating, though, as most large cathedrals and Eastern Orthodox churches don't.

the falls dump about 100,000 cubic feet of water per second (both american and canadian falls).

i dunno the volume, but i would guess it wouldn't take more than a few seconds.

oh man, thanks for setting me straight on that one LIG. Not sure how I got the cronology so botched on that one.

With loose chairs and tables, the building department will set maximum occupancy based on 15 SF per person. They'll probably also want a furniture plan to verify exit widths.

This article (Hagia Sophia) says the building occupies 7,500 square meters ... this page (Interactive Floor Plan) shows the floor plan.

while I recognize that all of the floor area is not worship space, perhaps by using a reasonable estimate of how much space one person occupies and how much of the total floor area is worship space, you can estimate the capacity of the space to accommodate worshipers.

Are you including megachurches in your survey? Some of those places are huge.

Thanks for the comments everyone. Its not a mega church study, weem. Actually the goal is to show churches of varying capacity as examples of what a "x-seat" church looks like.

What I need the most I realize now is examples of recognizable churches (to non-architects) in the 700-900 seat range. If anyone has any ideas please throw them this way...gently. Don't want to get poked in the eye by a spire, wocka wocka.