Glass Weight Calculator

Glass is heavier than people expect, and the moment that matters is the moment two people are holding a pane on a ladder. A single sheet of 10 mm glass two metres by one metre weighs 50 kg, which is at the limit of what two people should be lifting without gear. This calculator tells you the weight before you order, so you can plan the lift, size the fixings and check what the frame or the balustrade posts have to carry. Enter the length, width and thickness of the pane in millimetres, choose the material, and set how many panes you are handling. It returns the weight of a single pane, the total for the whole order, the area of each pane and the weight per square metre, which is the figure glaziers work from. The material list covers float and toughened glass, low iron glass, and the two common clear plastics, because acrylic and polycarbonate are less than half the weight and that often decides which one you use.

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mm
mm
mm
50 kg
total weight of the order
Weight per pane50 kg
Weight per square metre25 kg
Area per pane2 m²
Total area2 m²

Figures are for the glass itself. Laminated glass adds a small amount for the interlayer, and a double glazed unit weighs roughly the sum of its two panes plus the spacer. Anything over about 25 kg per person needs mechanical handling or more hands.

How it works

Weight is volume multiplied by density, and volume is length multiplied by width multiplied by thickness. Working in millimetres, a cubic millimetre of float glass weighs 2.5 milligrams, so the arithmetic is a single multiplication once the units line up.

The useful shortcut is the weight per square metre. Float glass runs at 2.5 kg per square metre for every millimetre of thickness. So 6 mm glass is 15 kg per square metre, 10 mm is 25, and 12 mm is 30. Once you know that number you can size any pane in your head.

Density is what separates the materials. Float and toughened glass are both 2,500 kg per cubic metre, because toughening changes the stress in the glass rather than its composition. Low iron glass is fractionally denser at 2,510. Acrylic is 1,190 and polycarbonate 1,200, which is why a plastic sheet of the same size is under half the weight.

Worked example

One pane of 10 mm toughened glass, 2,000 mm by 1,000 mm.

The area is 2,000 multiplied by 1,000, which is 2,000,000 mm2, or 2 m2. At 10 mm thick that is 20,000,000 mm3 of glass. Multiplied by the density of 2,500 kg per cubic metre, the pane weighs 50 kg.

Checked against the shortcut: 2.5 kg per square metre per millimetre, multiplied by 10 mm, is 25 kg per square metre. Two square metres at 25 kg is 50 kg, which agrees.

Fifty kilograms is a two-person lift at best, and awkward because the load is thin and wide rather than compact. The same pane in 10 mm acrylic would be 23.8 kg.

Related calculators

Data sources: Float glass 2,500 kg/m3, low iron glass 2,510 kg/m3, acrylic (PMMA) 1,190 kg/m3, polycarbonate 1,200 kg/m3, as published in manufacturer technical data sheets.

Frequently asked questions

How much does a square metre of glass weigh?

Float glass weighs 2.5 kg per square metre for every millimetre of thickness. So 4 mm glass is 10 kg per square metre, 6 mm is 15 kg, 10 mm is 25 kg and 12 mm is 30 kg.

Does toughened glass weigh more than ordinary glass?

No. Toughening is a heat treatment that changes the stress pattern inside the glass, not its composition, so a toughened pane weighs the same as an annealed pane of identical size and thickness.

How much lighter is acrylic than glass?

Acrylic has a density of about 1,190 kg per cubic metre against 2,500 for glass, so a sheet of the same size and thickness weighs roughly 48 per cent of the glass equivalent. A 50 kg glass pane becomes about 23.8 kg in acrylic.

How do I work out the weight of double glazing?

Calculate each pane separately and add them together, then allow a small amount for the spacer bar and sealant. A unit made of two 6 mm panes weighs close to 30 kg per square metre before the spacer.