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20mm vs 40mm Stone Benchtops: What's the Difference?

Cost estimates only: Any building, material or upgrade figures on this page are indicative, not fixed prices or quotes. Confirm current written costs, specifications and inclusions directly with your builder, supplier or relevant trade.

Overview

When reviewing new home inclusions, you'll frequently see benchtop thickness described as "20mm stone benchtop" or "40mm stone benchtop." These numbers refer to the visual thickness of the benchtop edge — and while the difference sounds minor, it has a significant impact on the overall look and feel of your kitchen.

Understanding what's actually included in your contract — and what the upgrade will cost — is one of the most common questions buyers have at their colour appointment.

Note

Benchtop thickness is one of the most commonly misunderstood inclusions. When a builder says "stone benchtop included," always ask what thickness is specified in the contract documents.

20mm Benchtops

A 20mm benchtop is the standard specification included in most project home packages. The stone slab is 20mm thick, which is practical and functional but has a relatively thin, lighter appearance when viewed from the side or on an island bench.

For wall-mounted benchtops (against a cabinet), the edge profile is less visible. However, on an island bench where the edge is fully exposed, a 20mm thickness can look quite slender compared to what you see in most design magazine kitchens.

Pros

Included in most base builder packages
Functional and practical for everyday use
Lower cost — no upgrade fee
Lighter weight on cabinets
Still looks good on wall-run benches

Cons

Thinner edge looks less premium on island benches
Less visual weight and presence in the kitchen
Less on-trend compared to 40mm in modern designs
Can appear dated in higher-end kitchen packages

40mm Benchtops

A 40mm benchtop has twice the visual edge thickness of a standard 20mm slab. This creates a more substantial, luxurious appearance — particularly on kitchen islands where the full edge profile is on display. It's one of the most popular kitchen upgrades in Australian new builds, and one of the most cost-effective ways to elevate a kitchen's overall look.

There are two ways to achieve a 40mm profile:

True 40mm slab: A single solid slab of stone at 40mm thickness. Heavier, more expensive, and genuinely thicker throughout.
Mitre edge (laminated): A 20mm slab with an additional 20mm strip bonded underneath the edge only. Achieves the same visual appearance at lower cost. This is the most common method used by builders.

Tip

When upgrading to a 40mm benchtop, ask your builder whether they use a true 40mm slab or a mitre edge. Both look the same from a distance, but understanding the construction method helps you compare quotes accurately between builders.

Side-by-Side Comparison

Factor	20mm	40mm
Visual weight	Slender / light appearance	Substantial, luxurious presence
Inclusion in base price	Usually included as standard	Almost always an upgrade
Typical upgrade cost	—	$500–$2,500 depending on size & material
Best application	Wall-run benches	Island benches & feature areas
Construction method	Single 20mm slab	True 40mm or mitre edge
Weight on cabinets	Lighter	Heavier (true 40mm) / similar (mitre)
Impact on resale appeal	Standard	Higher perceived value

Which Rooms Benefit Most from 40mm?

Not all benchtops need to be upgraded to 40mm. The visual payoff depends heavily on where the benchtop is and how much of the edge is visible.

Kitchen Island / Breakfast BarHigh
Highest priority — the edge is fully exposed and the impact is dramatic.
Kitchen Wall-Run BenchesMedium
Moderate — the edge is visible but not as prominent as an island.
Master Ensuite VanityMedium
Popular upgrade in premium builds. Adds luxury feel to the main bathroom.
Bathroom VanitiesLow–Medium
Lower priority unless bathroom aesthetics are a key concern.
Laundry BenchtopLow
Low priority — rarely visible and purely functional.

Included or Upgrade?

Typically Included

20mm Laminate or Porcelain Benchtop

The standard specification across most volume builder packages. Exact material varies by builder tier.

Typically an Upgrade

40mm Stone Benchtop (Mitre Edge or True 40mm)

Almost universally a paid upgrade. Typical cost: $500–$2,500 for a standard kitchen, depending on linear metres and material.

Typically an Upgrade

40mm Benchtop to Bathroom Vanities

Separate upgrade to match the kitchen specification. Ask your builder for individual pricing per wet area.

Common Builder Upgrades

Common Builder Upgrade

Kitchen Benchtop Thickness Upgrade (20mm to 40mm)

One of the most popular kitchen upgrades at colour selection appointments. The visual difference on an island bench is immediately noticeable. Typical cost range: $500–$2,500 for a standard kitchen, depending on stone type and linear metres.

Common Builder Upgrade

Waterfall Edge Addition

A waterfall edge (where the 40mm benchtop wraps continuously down the side of the island) is a premium design feature. Often quoted as a separate upgrade on top of the 40mm thickness upgrade. Cost range: $1,500–$5,000+ depending on island size and material.

Common Builder Upgrade

Matching 40mm Spec to Bathrooms

Matching the kitchen's 40mm specification across master ensuite and bathroom vanities creates a cohesive, premium feel throughout the home. Budget $300–$900 per bathroom depending on vanity size.

View Upgrade Cost Estimates →