How To Calculate The Weight Of Glass

Large double glazed sealed units can be quite heavy and triple glazed sealed units are almost 50% heavier so it can sometimes be useful to know how heavy your glass will be before deciding on the correct type of glass to order. 

As a rule of thumb a square metre of glass weighs 2.5kg per 1mm in thickness so standard 4mm glass will weigh 10kg for a square metre size piece of glass. Double glazed sealed units have twice the amount of glass and once you add the additional spacer bar and sealant, this takes the weight of a square metre of double glazed glass (using 4mm glass) up to around 22kg. 

Using this information, here are a few examples of glass weights for commonly requested sizes.....

A double glazed door panel glass measuring 600mm x 1000mm weighs 13.2kg

A double glazed full height door panel glass measuring 600mm x 1900mm weighs 25.08kg

A double glazed fanlight measuring 600mm x 300mm weighs 3.96kg

It is worth remembering that these are the weights of plain sealed units and do not take into acccount the extra weight added to the glass by lead strip, bevels or other decorative materials such as fused glass tiles. The above examples are calculated using the most commonly requested glass - 4mm glass. Here are the weights of other single sheet glass.....

Glass thickness Weight (m2)4mm 10 kg6mm 15 kg8mm 20 kg10mm 25 kg12mm 30 kg

Contact an architect or other professional person to calculate exact weights and dimensions for your project.

Weight of double glazed with12 mm cavity……………kg/m 2

4-12-4 ………………………………………………….20

6-12-6……………………………………………………..30

10-12-6 …………………………………………………….40

12-12-6 ……………………………………………………45

A sectioned diagram of a fixed Insulated Glazed Unit (IGU), indicating the numbering convention used in this article.

Surface #1 is facing outside, Surface #2 is the inside surface of the exterior pane, Surface #3 is the outside surface of the interior pane, and Surface #4 is the inside surface of interior pane. The window frame is labelled #5, a spacer is indicated as #6, seals are shown in red (#7), the internal reveal is on the right hand side (#8) and the exterior windowsill on the left (#9)