Glass thickness - don't want to over or under spec!!

My walls are: 2 x 16mm plasterboard on the control room side. 1 x 16mm plasterboard on the live room side. Seperate wooden frames with insulation in stud cavities. The air-gap between layers of plasterboard is 125mm in total. I don't want to over (or under) spec the glass for the windows. The airgap between the actual glass will be 125mm. What thickness glass do I need to order to keep up with the walls JohnG

Glas is about 3 x the weight of plasterboard, so you need 1/3 of the thickness of the wall construction.

thanks 10mm and 8mm it is. JohnG