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Glass thickness guide: what thickness do I need?

The glass thickness we suggest for shelves, showers, splashbacks, mirrors and table tops, how to work out weight, and when a design check is needed.

Written by the SW Glass team · Last updated

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The right glass thickness depends on what the glass is for. As a guide, shelves are 6, 8 or 10 mm depending on the span, shower glass is 8 or 10 mm, splashbacks are 6 mm, mirrors are 4 or 6 mm and table tops are 10 or 12 mm. Our glass thickness tool gives the pick for your job and says whether it is toughened.

What thickness does the thickness tool suggest?

These are the trade-standard picks the thickness tool gives for each use:

UseSuggested thicknessNotes
Shelf, span up to 500 mm6 mm toughenedSpan is the distance between supports
Shelf, span 500 to 800 mm8 mm toughened
Shelf, span over 800 mm10 mm toughenedCheck the sag calculator too
Table top10 mm toughenedThe standard for full glass table tops
Table protector6 mm toughenedProtects an existing surface
Splashback6 mm toughenedRequired behind hobs
Shower screen8 mm toughened10 mm for frameless
Balustrade10 mm toughened minimumNeeds a site-specific check, often 12 mm or laminated
Internal door10 mm toughenedFor frameless internal doors
Single-glazed window4 mm floatSafety glass if in a critical location
Mirror4 mm up to about 1 m; 6 mm larger6 mm for large or frameless mirrors
Greenhouse4 mm toughened

The tool's own disclaimer applies: this is guidance for planning, not a structural calculation. Balustrades, floors, overhead glazing and anything load-bearing need a site-specific design check. Confirm with your building inspector or engineer before you order.

Which thicknesses can I order for each product?

The configurator only offers the thicknesses each product allows:

  • Shower and bath glass: 8 or 10 mm, always toughened. Satin and fluted glass come in 10 mm only. A hinged door is 8 or 10 mm too, and the configurator offers only the hinges made for its thickness.
  • Splashback: 6 mm, always toughened.
  • Mirror: 4 or 6 mm, not toughened.
  • Shelf: 6, 8 or 10 mm. The shelf configurator does not offer toughening, although the thickness tool suggests toughened glass for shelves; ask us if you need a toughened shelf.
  • Table top: 10 or 12 mm, always toughened.

Why toughening matters is covered in toughened, laminated and annealed glass.

How heavy will my glass be?

Ordinary glass weighs approximately 2.5 kg per square metre for every millimetre of thickness. A 900 × 2000 mm pane at 10 mm is 0.9 × 2.0 × 10 × 2.5 = 45 kg. Laminates need their actual build-up considered.

Use the glass weight tool for planning. Its handling bands are not safe lifting limits. Assess the task, load, route and people; see HSE manual handling guidance.

How much will a glass shelf hold?

The shelf load tool takes the span, depth, thickness and how the shelf is held, and gives the load it carries spread evenly. Read its limits before you rely on it:

  • It is a planning guide, not a structural certification, and not a design to BS EN 16612.
  • It assumes the load is spread evenly, the edges are clean and polished, and the fixings carry the load.
  • A heavy object at the centre, a chipped edge or a weak bracket all reduce what the shelf holds.
  • It does not cover a shelf held only along its back edge in a wall channel.

Where the load matters, ask us for a specification and have anything load-bearing checked by an engineer.

When do I need a design check?

You need a site-specific design check for balustrades and barriers, glass floors, overhead glazing and anything load-bearing. Our tools do not replace that check, and their results are not a structural design. Our balustrades guide explains which balustrade designs are priced online and which we price by hand.

Give the support details with the dimensions

A thickness recommendation is incomplete without knowing how the pane is supported and loaded. For a shelf, describe bracket positions and what it will carry. For a table top, show the base and overhang. For guarding, provide the complete system and the structure receiving its fixings.

Do not use a thicker pane to compensate for an unknown fixing or unsupported span. Extra thickness also adds weight, which can increase the demand on hinges, brackets and handling arrangements.

Keep the supplier's limits and any engineer's specification with the order. Our balustrade specification guide lists the information needed for guarding; it is a different assessment from choosing a household shelf.

Where to go next

Check your pick with the glass thickness tool.

Questions we get asked

Is 8 mm or 10 mm better for a shower screen?

8 mm toughened is the wetroom standard and 10 mm suits frameless screens. Satin and fluted glass come in 10 mm only.

How do I work out the weight of a glass panel?

Multiply the area in square metres by the thickness in millimetres, then by 2.5 kg. A 1.8 m² panel of 10 mm glass weighs 45 kg.

Can I use the shelf load result as a structural design?

No. It is a planning guide that assumes an evenly spread load. Ask us for a specification and have anything load-bearing checked by an engineer.

Contact the team with your order reference and the step you need help with, or search all help topics.

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