Choosing the right glass thickness is important for safety, strength and appearance. Glass that is too thin can bend, break or feel unsafe. Glass that is too thick is often more expensive, heavier and sometimes difficult to install. The best glass thickness depends on what you use the glass for. The short rule is: the larger the glass plate, the less support and the more intensive use, the thicker the glass should be.
In this article we explain which glass thickness you need for windows, shower walls, table tops, mirrors, shelves, balustrades and other applications — including tables, weights and a quick selection aid.
Core rule of thumb: larger, less supported and more intensive use means thicker glass. And please note: thick glass is not automatic safety glass. You choose safety with the right glass type, not just with more millimeters.
Why is glass thickness important?
Glass may always seem the same, but its thickness makes a big difference. A glass plate of 4 mm behaves very differently than a glass plate of 10 or 12 mm. Glass thickness affects:
- strength and deflection;
- weight and carrying capacity;
- safety;
- appearance;
- assembly and suitable fittings;
- price;
- edge finishing.
With custom glass you do not simply choose the thickness. You look at the application, size, load and method of attachment. In the configurator you can immediately see which thicknesses are available per glass type.
What glass thickness is standard?
| Glass thickness | Commonly used application |
|---|---|
| 4 mm | Small windows, mirrors, cabinet glass |
| 5 mm | Slightly larger windows or interior glass |
| 6 mm | Table protection, kitchen back wall, shelf |
| 8 mm | Shower enclosure, larger interior glass, table top |
| 10 mm | Shower enclosure, glass door, table top |
| 12 mm | Large table top, wall, heavy duty |
| 15 mm | Large heavy table tops or special applications |
| 19 mm | Very heavy and luxurious applications |
These are general guidelines. The correct thickness always depends on the situation.
Glass thickness for windows
Windows are not just about thickness, but also about insulation, safety and frame space. A standard single-pane pane is often 4 mm thick. Insulating glass is much thicker because it consists of several glass plates and a cavity.
| Type of glass | Commonly used thickness |
|---|---|
| Single glazing | 4–6 mm |
| Old double glazing | 12–20 mm |
| HR++ glass | 24–28 mm |
| Triple glass | 36–42 mm |
| Vacuum glass | 8–12 mm |
With windows, you should especially check whether the glass fits in the frame. The rebate depth determines what thickness is possible. Do you want to replace single glass with HR++ glass? Then the new window is much thicker than the old one. Sometimes adapted glazing beads, covering beads or nose slats are required. Read more in Thicker insulating glass in an existing frame.
Glass thickness for HR++ glass
HR++ glass is usually between 24 and 28 mm thick. The exact thickness depends on the glass structure. An example of a HR++ structure is 4-15-5:
- 4 mm glass;
- 15 mm cavity;
- 5 mm glass.
Together that is 24 mm. With HR++ glass, you don't choose the thickness just based on feeling. The structure is determined by insulation value, glass size, safety and frame space. NB:
- Does the total thickness fit in the frame?
- Is the rebate deep enough?
- Are the glazing beads suitable?
- Is the window too heavy for rotating parts?
- Is safety glass necessary?
View the offer at insulating glass.
Glass thickness for vacuum glass
Vacuum glass is much thinner than HR++ glass or triple glass. vacuum glass is often approximately 8 to 12 mm thick, while still insulating very well. That is why vacuum glass is interesting for:
- old window frames;
- narrow rebates;
- monumental homes;
- renovations;
- situations where HR++ glass does not fit.
The thickness may look more like old single or thin double glazing, but the insulating effect is much better.
Glass thickness for shower walls
toughened safety glass is usually used for shower walls. The most commonly chosen thicknesses are 8 mm and 10 mm.
| Thickness | When to choose? |
|---|---|
| 6 mm | Small shower enclosure with profile |
| 8 mm | Most often chosen for standard shower walls |
| 10 mm | Luxurious appearance and extra strength |
| 12 mm | Usually only for special applications |
For most walk-in showers, 8 mm tempered glass is sufficient. It is sturdy, easy to handle and suitable for many profiles and stabilizing bars. 10 mm glass feels heavier and more luxurious and is often chosen for larger shower walls or when you want to see little profile.
Note: Thicker glass is heavier. The wall, floor, clamps and stabilizing bar must be suitable for this. View the options under shower and bath.
Glass thickness for shower doors
A shower door must be able to move. That is why the combination of glass thickness and fittings is important. Commonly used thicknesses are 8 mm and 10 mm.
For shower doors, 8 mm is often practical: sturdy enough for many applications, but less heavy than 10 mm. For larger doors or luxury fittings, 10 mm can be nice. Always check whether the hinges are suitable for the glass thickness and weight.
With tempered glass, all holes and hinge recesses must be made in advance. Retrospective adjustment is not possible — read why in Tempered glass: what is it?.
Glass thickness for glass doors
Tempered glass of 8, 10 or 12 mm is often used for glass interior doors.
| Door type | Commonly used thickness |
|---|---|
| Small closet door | 6 mm |
| Glass interior door | 8–10 mm |
| Pivot door | 10–12 mm |
| Large glass door | 10–12 mm |
| Sliding door | 8–10 mm |
The correct thickness depends on door size, hinge type, weight, fittings, direction of rotation, desired appearance and safety. A larger glass door often feels better in 10 mm glass. For high or wide doors, 12 mm may be necessary.
Glass thickness for table tops
With table tops it makes a big difference whether the glass is fully supported or forms the top itself.
| Application | Commonly used thickness |
|---|---|
| Protective plate on existing table | 4–6 mm |
| Desk glass as a protective plate | 4–6 mm |
| Coffee table on frame | 6–8 mm |
| Separate table top on base | 10–12 mm |
| Large dining table | 10–15 mm |
| Heavy luxury table | 15–19 mm |
Is the glass completely on a wooden table top? Then 4 or 6 mm is often sufficient. Does the glass only rest on legs or a base? Then you need thicker glass, often 10 or 12 mm. Preferably use tempered glass for table tops, especially if the top is loose or is used intensively.
Glass thickness for mirrors
Size mirrors are usually made of 4 or 6 mm mirror glass.
| Mirror type | Commonly used thickness |
|---|---|
| Small mirror | 4 mm |
| Bathroom mirror | 4 mm |
| Large wall mirror | 6 mm |
| Full-length mirror | 4–6 mm |
| Gym mirror | 6 mm or safety mirror |
| Mirror on cupboard door | 4 mm |
For most bathroom mirrors, 4 mm is sufficient. With larger mirrors, 6 mm feels sturdier and more luxurious. For large mirrors, also pay attention to the weight and mounting, and always use a suitable mirror kit or mirror mounting.
Glass thickness for glass shelves
With glass shelves, the thickness is important for load-bearing capacity. A shelf that carries books, crockery or decorations must be sufficiently strong.
| Application | Commonly used thickness |
|---|---|
| Small decoration shelf | 6 mm |
| Bathroom shelf | 6–8 mm |
| Cupboard shelf | 6–8 mm |
| Heavier shelf | 8–10 mm |
| Wide plank with little support | 10–12 mm |
The load-bearing capacity depends not only on thickness, but also on width, depth, length, number of carriers, distance between carriers, type of load, edge finish and type of glass. Preferably use ground edges for shelves, because they are visible and touchable — see Edge finishing: sharp edges or ground.
Glass thickness for kitchen back walls
6 mm tempered glass is often used for a glass kitchen back wall. This is usually sufficient for a smooth wall behind the worktop or hob. Choose tempered glass because a kitchen back wall has to deal with heat, moisture, cleaning, grease, temperature differences and impacts.
You must pay extra attention when using applications close to an open flame. Tempered glass can withstand temperature differences well, but is not the same as special heat-resistant stove glass.
Glass thickness for balustrades
The correct glass thickness is extra important for balustrades. This is not just about appearance, but about safety and fall protection. Never use just standard glass for a balustrade.
Balustrade glass is often laminated safety glass or tempered-laminated glass. The correct structure depends on:
- height difference;
- mounting system (glass clamps, point holders, profile system);
- inside or outside;
- wind load;
- dimensions and load;
- regulations.
Customized advice is important for balustrades. A thin sheet of glass may look good, but be unsafe if the construction is not correct. You can read more about the choice in Toughened or laminated glass.
Glass thickness for windshields
Tempered or laminated safety glass is often used for wind screens. The thickness depends on height, width and wind load. Commonly used thicknesses are 8 mm, 10 mm, 12 mm and layered structures for higher requirements.
For outdoor use, take wind, mounting, glass clamps, post distance, height, safety and corrosion-resistant fittings into account. The larger the screen and the greater the wind load, the heavier the design must be.
Glass thickness for display cabinets
4, 5 or 6 mm glass is often used for display cabinets. For sliding doors, 4 or 6 mm is common, depending on the size.
| Application | Commonly used thickness |
|---|---|
| Small display window | 4 mm |
| Sliding doors | 4–6 mm |
| Larger closet door | 6 mm |
| Shelf in display case | 6–8 mm |
With sliding doors it is important that the glass fits in the profile. Glass that is too thick cannot slide; Glass that is too thin feels fragile. For visible and touchable edges, choose flat poly-cut glass.
Glass thickness and weight
The thicker the glass, the heavier it becomes. Glass weighs on average approximately 2.5 kg per m² per millimeter of thickness.
| Thickness | Weight per m² |
|---|---|
| 4 mm | ± 10 kg |
| 6 mm | ± 15 kg |
| 8 mm | ± 20 kg |
| 10 mm | ± 25 kg |
| 12 mm | ± 30 kg |
| 15 mm | ± 37.5 kg |
| 19 mm | ± 47.5 kg |
With large glass plates, the weight can quickly increase. Therefore, always check whether you can safely lift the glass and whether the construction can support the weight. Calculate your situation exactly in Calculate glass weight.
Is thicker glass always better?
No. Thicker glass is not automatically better — it must suit the application.
Benefits of thicker glass:
- firmer feeling;
- less deflection;
- more luxurious appearance;
- more weight and stability.
Disadvantages of thicker glass:
- more expensive;
- heavier;
- more difficult to assemble;
- not always suitable for profiles;
- heavier for hinges;
- sometimes unnecessary.
So don't blindly choose the thickest option. Choose the thickness that is technically and practically correct.
Tempered, laminated or normal glass?
The glass thickness is just one part. The type of glass is just as important.
| Type of glass | When to use? |
|---|---|
| Normal glass | Simple applications without security risk |
| Tempered glass | Shower walls, doors, table tops, kitchen back walls |
| Laminated glass | Low windows, roof glass, balustrades, risk of falling through |
| Tempered-laminated glass | Heavy security applications |
| Insulating glass | Windows and energy saving |
| Mirror glass | Mirrors and interior |
A thick pane of normal glass is not automatically safety glass. For safety, choose the right glass type, not just more thickness.
Common mistakes when choosing glass thickness
- Just look at the price — glass that is too thin can feel unsafe or flimsy; choose the thickness appropriate for the application.
- Thinking that thick glass is always safety glass — thick standard glass can still break into sharp shards.
- Forgot weight — large panes of glass can be heavy; check mounting and load-bearing capacity.
- Selecting the wrong hardware thickness — hinges, clamps and profiles are suitable for specific glass thicknesses.
- Do not consider support — a fully supported slab may be thinner than a free-span slab.
- No safety structure on balustrades — laminated safety glass is required if there is a risk of falling through.
- HR++ choose glass without checking the frame space — insulating glass must fit in the rebate.
Quick selection aid for glass thickness
| Project | Recommended starting point |
|---|---|
| Small mirror | 4 mm |
| Large mirror | 6 mm |
| Protective glass on the table | 4–6 mm |
| Separate table top | 10–12 mm |
| Shower enclosure | 8 mm |
| Luxury shower enclosure | 10 mm |
| Glass door | 8–10 mm |
| Kitchen back wall | 6 mm hardened |
| Small display cabinet | 4 mm |
| Glass shelf | 6–8 mm |
| Windshield | 8–10 mm or more |
| Balustrade | Project-dependent safety glass |
| HR++ glass | Often 24–28 mm |
| Vacuum glass | Often 8–12 mm |
| Triple glass | Often 36–42 mm |
Use this table as your initial direction. Then always check the exact application, dimensions and mounting.
Checklist: what glass thickness do I need?
- What do I use the glass for?
- Is the glass fully supported?
- How big is the glass plate?
- Is the glass heavily loaded?
- Is safety glass necessary?
- Is there a risk of falling through?
- Does the glass come inside or outside?
- Does the glass have to fit into a profile?
- Which batter do I use?
- Can the structure support the weight?
- Are the edges visible and is edge finishing necessary?
- Should there be holes or recesses?
- Does the thickness fit in the frame or system?
Conclusion
The correct glass thickness depends on application, size, support and safety. For small mirrors, 4 mm is often sufficient. 8 or 10 mm tempered glass is usually used for shower walls. For loose table tops you often choose 10 or 12 mm. For HR++ glass, triple glass and vacuum glass, the insulating structure determines the total thickness.
Thicker glass is not automatically better: it is heavier, more expensive and does not always fit in profiles, frames or fittings. Therefore, always choose the thickness that suits the application. In addition to thickness, also pay attention to the type of glass — tempered glass is often wise for doors, shower walls and table tops, laminated safety glass is important for balustrades, roof glass and fall hazards.
Read also: Toughened or laminated glass · Tempered glass: what is it? · Measuring glass · Calculating glass weight
Do you know what thickness you need? Configure your glass in the custom-made glass configurator — you can immediately see which thicknesses are available per type.