I tried to use the aquatools calculator it doesn't work it keeps bringing me to ads
So for a larger tank I should use Laminated Annealed GlassIt appears some of the original calculator sites are not being maintained, which is unfortunate. The GARF site (www.garf.org) has changed so their tank calculator, which provides glass thickness, is a bit harder to find (http://www.garf.org/navagation.html).
Here's a bit of a technical site on aquarium glass thickness calculations, however it's in the UK so the specs are all metric. A basic metric converter utility can deal with this of course.
I'm no glass engineer/expert. The info at that UK site seems to recommend laminated glass for large panels. I think laminated glass is what you see in car windshields, so instead of blowing apart, it is supposed to fracture as a sheet and therefore leak if stressed. His analogy for tempered (toughened) glass is pretty graphic--with water pressure behind the little shattered bits--would be like a shotgun blast.So
So for a larger tank I should use Laminated Annealed Glass