Reviewed by Clarrie King, licensed stonemason · Premier Stone, Drouin VIC · Updated June 2026
A 20mm benchtop is a single slab thickness with a slim, modern profile and the lower cost. A 40mm benchtop is usually a 20mm slab with a mitred edge built up to look 40mm, giving a heavier, premium appearance for islands and bar tops. The work surface performs the same either way. The difference is the edge look and the cost of the extra fabrication.
Thickness is one of the first decisions a fabricator will ask you about, and it shapes both the look and the quote. Here’s how to choose, and the common trick of mixing both in one kitchen.
Planning a kitchen in Melbourne’s south-east? Premier Stone advises on thickness and edge during templating, from our Drouin workshop. See our benchtop services → or call 1300 282 065.
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What’s the real difference between 20mm and 40mm?
Stone benchtops are most often supplied as 20mm slabs. A “40mm benchtop” is rarely a solid 40mm piece of stone. Instead, the fabricator mitres a strip of the same slab under the front edge so the bench reads as 40mm thick while staying lighter and more economical than solid stone. So both options start from the same 20mm material; the 40mm look is created at the edge.
20mm vs 40mm: side by side
| Factor | 20mm | 40mm (mitred) |
|---|---|---|
| Look | Slim, modern, minimal | Substantial, premium |
| Cost | Lower | Higher (more stone + labour) |
| Best for | Contemporary kitchens, splashbacks | Islands, bar tops, feature edges |
| Performance | Strong when supported | Same work surface |
The smart compromise: mix both
Many Melbourne kitchens use a 20mm top on the perimeter runs and a 40mm mitred edge, or a waterfall edge, on the island as a single feature. You get a premium centrepiece where it counts without paying for a thick edge on every run. It’s the most cost-aware way to get the substantial look. For more on edge and dimensions, see our benchtop dimensions guide.
Frequently Asked Questions
What is the difference between a 20mm and 40mm stone benchtop?
A 20mm benchtop is a single slab thickness with a slim profile. A 40mm benchtop is usually a 20mm slab with a mitred edge built up to look 40mm, giving a heavier appearance. The work surface performs the same; the difference is the edge look and fabrication cost.
Is a 20mm or 40mm benchtop better?
Neither outright. 20mm suits contemporary kitchens and costs less; 40mm gives islands a substantial, premium look. Many kitchens use 20mm on perimeters and a 40mm edge on the island.
Does a 40mm benchtop cost more?
Usually yes. A built-up 40mm mitred edge uses more stone and labour than a 20mm top. The extra cost is for the look, not performance.
Is a 20mm benchtop strong enough?
Yes, when properly supported by the cabinets. Overhangs like a breakfast bar may need a bracket regardless of thickness. A fabricator advises during templating.
What thickness is best for a kitchen island?
Islands are where a 40mm mitred edge has the most impact. A waterfall edge also reads beautifully. A 40mm or waterfall island over a 20mm perimeter is a popular, cost-aware choice.
More guides from Premier Stone:
- Standard Kitchen Benchtop Dimensions
- How Much Do Stone Benchtops Cost in Melbourne?
- Kitchen Benchtop Materials Compared
- Stone Benchtops Melbourne: Prices and Free Quote
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