12mm vs 20mm Stone Benchtops: Which Thickness to Choose
Reviewed by Team Asetica · Sydney · Perth · Melbourne · Updated August 2026
Pictured: Loro White
Choose 20mm sintered stone for kitchen benchtops and islands, and 12mm for splashbacks, vanities, furniture, cladding and vertical surfaces. Asetica supplies both thicknesses in the same 3200mm by 1600mm slab format. The material is identical. Only span, weight and edge appearance change.
Thickness is one of the first decisions in a benchtop specification, and the one most often mistaken for a quality difference. This guide covers when each thickness is correct, how a mitred edge lets a 12mm slab read as 40mm, and what actually moves the price.
- 20mm for benchtops and islands. 12mm for splashbacks, vanities and vertical work.
- Same material at both thicknesses: non-porous, UV stable, never sealed.
- A 12mm slab is about 40% lighter than 20mm over the same area.
- 40mm and 60mm edges are mitred, not solid slab. Asetica slabs are 3200mm by 1600mm.
Specifying a benchtop? View full slabs in both thicknesses and order free samples at our Sydney and Perth showrooms. View the Collection
12mm vs 20mm at a Glance
| 12mm | 20mm | |
|---|---|---|
| Best for | Splashbacks, vanities, vertical panels, furniture, cladding | Kitchen benchtops, islands, outdoor kitchens |
| Look | Slim and contemporary | Substantial, reads as solid stone |
| Weight | About 40% lighter | Heavier. Confirm cabinetry can carry it |
| Mitred edge | Yes, to build apparent thickness | Yes, for 40mm and 60mm looks |
| Slab format | 3200mm by 1600mm | 3200mm by 1600mm |
When 20mm Is the Right Call
20mm is the default for horizontal kitchen surfaces in Australia. It carries the visual weight most clients expect from a stone benchtop, handles unsupported spans around sinks and cooktops more comfortably, and accepts a wider range of edge profiles without a mitre. Specify 20mm for island benches, main runs, outdoor kitchens, and anywhere the edge is read at close range from standing height.
When 12mm Is the Better Choice
12mm is not a lesser product. It is the correct specification wherever weight, thickness or a slimline profile matter more than bulk. At about 40% lighter than 20mm over the same area, it also solves handling and load problems that 20mm creates.
- Splashbacks. A full-height 12mm splashback in the same design as the benchtop removes grout lines entirely.
- Vanities and bathrooms. Shorter spans, lighter substrate, easier handling in tight rooms.
- Furniture and dining tables. Less mass on the frame.
- Cladding and facades. Vertical applications where every kilogram counts.
- Renovations. Where existing cabinetry was never built to carry a heavier top.
How to Make 12mm Look Like 40mm
A mitred edge is how a thin slab reads as a thick one. The fabricator cuts the benchtop and the edge strip at 45 degrees and joins them, so the apparent thickness is whatever you specify while the slab itself stays 12mm or 20mm. Most 40mm and 60mm benchtops in Australian kitchens are built this way rather than cut from solid slab.
Thickness and edge profile are therefore separate decisions. See our guide to benchtop edge profiles for pencil round, arris, mitred and the rest.
Does Thickness Change Performance?
No. Sintered stone is the same material at 12mm and 20mm: non-porous, so it never needs sealing, UV stable, so it will not yellow outdoors, and resistant to heat, staining and scratching. Thickness affects span, weight and appearance, not the surface itself. For the full background on the material, see what is sintered stone.
Frequently Asked Questions
Can you use 12mm stone for a kitchen benchtop?
Yes, provided the cabinetry gives continuous support and any cutouts are reinforced by the fabricator. 12mm benchtops are common in contemporary kitchens, usually with a mitred edge to build visual thickness. For long unsupported spans or heavy-use islands, 20mm is the safer specification.
Is 20mm stronger than 12mm?
The material is identical at both thicknesses, so it is not stronger by composition. A 20mm slab is more rigid and tolerates greater unsupported spans. The practical difference shows up around sink and cooktop cutouts, and on overhangs.
What thickness are most Australian kitchen benchtops?
20mm is the most common thickness for benchtops and islands in Australia. 12mm is standard for splashbacks and vertical work. Finished edges of 40mm and 60mm are usually mitred from one of those two thicknesses rather than cut from a solid slab.
Does thickness change the price of a benchtop?
A 20mm slab costs more than a 12mm slab in raw material, but fabrication usually matters more than thickness. A mitred 12mm benchtop with a 40mm apparent edge can cost more than a plain 20mm top. Quote on the finished detail, not the slab alone.
How big are sintered stone slabs?
Asetica sintered stone slabs are 3200mm by 1600mm in both 12mm and 20mm thickness. That format is large enough to run most kitchen islands as a single piece with no join.
Can 12mm sintered stone be used outdoors?
Yes. Sintered stone is UV stable and freeze thaw resistant at both 12mm and 20mm, so it will not fade or yellow outdoors. For outdoor kitchen benchtops, 20mm remains the usual choice for span and edge presence.
More guides from Asetica:
- Kitchen Benchtop Edge Profiles: Pencil Round, Arris, Mitred and More
- What Is Sintered Stone? Properties, Uses and Comparisons
- Porcelain Benchtops: The Complete Australian Guide
Asetica Surfaces is a trade sintered stone supplier serving architects, builders, stonemasons, cabinet makers and designers across Sydney, Perth and Melbourne. Our team draws on hundreds of completed benchtop, splashback and facade projects. Every guide is checked against current Australian standards and the engineered stone regulations in force since 1 July 2024. See the range at our Sydney (Padstow) and Perth (Subiaco) showrooms, or call 1300 161 388.
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