Glass · Thickness
How thick should glass be?
It depends on the use and the load: 4 to 6 mm in an ordinary window, 8 or 10 mm toughened for a frameless shower, 10 or 12 mm for a glass door, laminated 17.5 to 21.5 mm for a balustrade. The table gives the thickness the trade usually fits for each use and what decides it. Where the size or the load matters, the thickness is a calculation, and each row links to the calculator that does it with the standard's numbers.
Glass thickness by use
| Use | Usual thickness | What decides it | Work it out |
|---|---|---|---|
| Window pane, single glazed | 4 to 6 mm | Size of the pane and the wind on it | Thickness under wind load |
| Double glazing, each pane | 4 to 6 mm (laminated 6.4 on the outside where safety glass is needed) | Size, wind and where safety glass is required | Glazing configurator |
| Large facade or shop front | 8 to 12 mm, often laminated | Wind load and span | Thickness under wind load |
| Glass balustrade or barrier | Laminated toughened, 17.5 to 21.5 mm (2 × 8 or 2 × 10) | The line load people put on it and the fixing | Balustrade calculator |
| Pool fence | 12 mm toughened | Height, panel width and the spigot maker's table | Glass pool fence |
| Shower screen or door, frameless | 8 or 10 mm toughened | Size, hinges and the fixed panel | Shower door and hinges |
| Interior glass door, frameless | 10 or 12 mm toughened | Width, height and the fitting's rating | Glass door weight |
| Table top | 8 to 12 mm toughened | Span between supports and the load | Table and shelf |
| Shelf | 6 to 10 mm toughened | Span, depth and what sits on it | Table and shelf |
| Aquarium | From 6 mm (small) to 19 mm and more | Water height, length and bracing | Aquarium glass thickness |
| Mirror | 4 mm (6 mm for large ones) | Size and how it is fixed | Mirror weight |
| Walk-on floor or stair tread | Laminated, three or more plies | An engineer's calculation: not a table | Where safety glass is required |
Usual choices of the trade, not a calculation: a pane larger than usual, a stronger wind or a heavier load needs a thicker glass, and the calculators say how much.
Three things that change the answer
- Size. Stress and deflection grow fast with the span: double the short side of a pane under wind and it needs much more than double the strength.
- The load. Wind on a facade, people leaning on a barrier, books on a shelf and water in a tank are different loads, and each has its own standard.
- Where it is. In doors, low windows, showers and barriers the glass has to be safety glass, toughened or laminated, whatever its thickness.
What this page does not do
- It does not size a pane. That is what the calculators linked in the table are for.
- It does not replace the engineer for walk-on glass, structural fins or anything that carries people.
Questions people ask
- How thick should window glass be?
- 4 to 6 mm for ordinary windows, single or in each pane of double glazing; larger panes and windy sites need more, which the wind load calculator works out.
- What thickness of glass is used for a glass door?
- 10 or 12 mm toughened for a frameless door; framed doors often use 6 mm laminated or toughened in the frame.
- How thick is glass for a shower screen?
- 8 or 10 mm toughened for frameless shower screens and doors; 6 mm where the glass sits in a frame.
- How thick should a glass table top be?
- 8 to 12 mm toughened, depending on the span between supports and the load; the table and shelf calculator checks a size.