Glass weighs 2.5 kg per square metre per millimetre of thickness. A 2.4 m x 1.2 m panel of 10 mm glass weighs 72 kg, and that number decides the hinges, the channel, the lifting plan and often the structure.
The formula
Weight in kilograms equals width in metres x height in metres x thickness in millimetres x 2.5. The constant is derived from the density of soda-lime float glass, and it is accurate enough for hinge selection, channel sizing and transport planning. Laminated glass adds the interlayer, so a 6.38 mm laminated pane is specified as 6 mm for weight purposes and weighs marginally more than the formula gives: treat it as 6 mm plus a small allowance.
Worked examples
| Panel | Calculation | Dead weight |
|---|---|---|
| 2.4 m x 1.2 m, 10 mm toughened sliding door | 2.4 x 1.2 x 10 x 2.5 | 72.0 kg |
| 2.0 m x 0.9 m, 8 mm frameless shower door | 2.0 x 0.9 x 8 x 2.5 | 36.0 kg |
| 1.8 m x 1.2 m, 6 mm laminated balustrade panel | 1.8 x 1.2 x 6 x 2.5 | 32.4 kg |
| 2.4 m x 2.4 m, 12 mm toughened fixed screen | 2.4 x 2.4 x 12 x 2.5 | 172.8 kg |
Use the calculator, then check the fixing
Our glass weight calculator does this arithmetic for any size and thickness in the catalogue. The formula tells you the mass; the engineering question is where that mass goes, which is the hinges, the track, the clamps and the slab.
Where dead weight decides the design
- 01Hinges and pivots on a frameless door: two hinges on a 45 kg panel carry a very different load from two hinges on a 20 kg panel.
- 02Sliding door tracks: the runner and the track must carry the panel weight plus the dynamic load of every open and close.
- 03Base-channel balustrades: the shoe and its anchors carry the panel weight and the line load together.
- 04Lifting and installation: a 170 kg fixed screen is a crane or a team of four, planned before the day, not discovered on it.
- 05Suspended or overhead glazing: the structure above must be designed for the glass, not assumed capable of it.
- 06Transport and crating: weight limits per crate, and the route into the building before the panel is made.
Weight is also a safety number
A panel that is too heavy for its hardware does not fail dramatically on day one. It sags, the hinge wears, the door stops closing, and eventually the fixing pulls out of a wall that was never designed to receive the load. Sizing hardware off the dead weight at quoting stage is the cheapest form of liability insurance available.