How much benchtop stone do you actually need?
A typical Mandurah kitchen needs 5 to 6.5m² of finished benchtop, which is two 3200 x 1600mm slabs once the cutting plan is allowed for, not one. Measure each run in millimetres, multiply length by depth, divide by a million, then add 10 to 25 per cent for shape. The estimator below does that arithmetic and puts a 2026 dollar range on the answer.
Size your job, then price it
Enter the finished areas you measured. The quantities stay visible beside each field so you can see how big the job is, not just what it costs.
What this estimator assumes
- Rates are supplied and installed for Mandurah and the Peel in 2026, based on 20mm stone with a square or small pencil edge.
- The area you enter is finished benchtop, measured to the front of the overhang. The offcut allowance is added on top of that.
- Excludes licensed plumbing and electrical disconnection and reconnection, which is $400 to $1,000 if the sink or cooktop moves.
- Excludes tiled splashback removal and any cabinetry work, and assumes reasonable access for carrying a slab in.
- This page sizes the job. For the itemised rate card, use the pricing guide and the Mandurah cost guide.
How to measure it properly with a tape and a phone
Ten minutes with a tape gets you within a few per cent, which is close enough to reserve slabs and set a budget. Work in millimetres the whole way through, because that is how a fabricator thinks and it stops the rounding errors that turn a one slab job into a two slab job.
- Sketch the plan first. A rough overhead sketch of the kitchen on paper, one line per run, before you touch the tape. Number the runs A, B and C.
- Measure each run wall to wall. Not cabinet to cabinet. Include the return where the bench turns a corner, and count that corner once, not twice.
- Measure the depth at the front edge. Standard Australian base cabinets give a finished bench of 600mm to 650mm including the overhang. Islands with seating run 900mm to 1100mm. Measure, do not assume.
- Photograph every corner with the tape in shot. It costs nothing and it settles arguments later. Photograph the sink, the cooktop and the dishwasher gap too.
- Convert to square metres. Length in mm times depth in mm, divided by 1,000,000. A 3,600 by 620 run is 2.23m².
- Add the splashback separately. Length by height. Bench to the underside of the overheads is usually 600mm, and full height behind a cooktop is 700 to 900mm.
Note the appliance gaps while you are there: a dishwasher opening is normally 600mm, a freestanding cooker is 600mm or 900mm, and the fridge space is whatever the previous owner left you. If the cooktop is gas, the clearance from a burner to any combustible surface is set by the gas installation standard AS/NZS 5601.1, which is one of the reasons a stone splashback is the easy answer behind a gas hob. If anyone in the house needs a different working height, read accessible benchtop heights before you finalise anything.
Slab sizes, yield and the allowance to add
The common engineered stone and porcelain jumbo slab is about 3200mm by 1600mm, which is 5.12m² gross. Older ranges and some natural stone come in around 3050 by 1400mm, or 4.27m². Granite and marble vary slab to slab, typically 2600 to 3200mm long by 1600 to 1900mm. None of that is the number that matters, though, because you never get the full slab as finished top. Real yield is 70 to 85 per cent once the square ends, the saw kerf and the awkward shapes are cut out, so plan on 3.6 to 4.3m² of finished benchtop per jumbo slab.
On top of yield, add an allowance for the cutting plan: about 10 per cent for a straight galley, 15 to 20 per cent for an L or a U, and 25 per cent or more when the veining has to run continuously across an island and up a splashback. A mitred waterfall end is its own piece, roughly bench depth by 900mm, so allow about 0.85m² per side on a 950mm island, which is covered on the waterfall island page. If there is usable material left, that is where a laundry top or a vanity comes from, and it is the cheapest stone you will ever buy.
Send us your sketch and we will check the slab count
Photograph your measurements and send them through. We will tell you how many slabs the job needs and where we would put the join, in writing, within one business day.
The sizing mistake that costs the most here
Assuming a long run comes out of one slab. A 3200mm slab does not yield a 3300mm finished piece, and once the ends are squared and the saw kerf is taken out you are realistically limited to about 3.1m in one piece. Plenty of Mandurah kitchens, especially the long single wall runs in 1990s Greenfields and Meadow Springs homes, land at 3.2m or 3.4m. That extra 100mm to 300mm is the difference between one seamless bench and either a visible join or a second slab. It is worth knowing before you fall in love with a colour that only comes in the smaller format.
The other three we see weekly. Forgetting the overhang, so the area comes out 5 per cent light across the whole job. Measuring an island at cabinet width rather than finished width, which misses the 300mm knee overhang that a seating island needs and which also needs support brackets. And buying a separate slab for the laundry or a vanity when the kitchen offcut would have covered both, which is why we ask what else is in the house before we cut anything. See the laundry benchtops and splashbacks pages for what those pieces usually consume.
Worked example: a 1990s Meadow Springs kitchen
Standard brick and tile home, L shaped kitchen against two walls with a separate island, sink and cooktop staying where they are. Here is the whole arithmetic.
- Run A: 3,600mm long by 620mm deep, which is 2.23m².
- Run B: 2,400mm by 620mm, which is 1.49m².
- Island: 2,400mm by 950mm, which is 2.28m².
- Finished benchtop total: 6.0m².
- L shape plus island allowance at 12 per cent: 6.72m² of slab to buy.
- At 3.6 to 4.3m² of usable top per 3200 x 1600mm slab, that is two slabs.
- One mitred waterfall end on the island: about 0.85m² more, taken from the second slab.
- Offcut left over: enough for a laundry top or two vanity tops in most cases.
In mid range compliant engineered stone at $650 to $900/m², 6.0m² with the 12 per cent allowance prices at roughly $4,400 to $6,050. Add an undermount sink cut-out at $180 to $350, a cooktop cut-out at $120 to $250, one waterfall end at $600 to $1,200, and removal and disposal of the old laminate at $150 to $400. The realistic all in figure for that kitchen is $5,400 to $8,250, which is exactly where the mid tier on our budget page sits. If the old top turns out to be legacy engineered stone, add $200 to $600 for compliant controlled removal.
The honest limit on all of this: your measurements are for budgeting and for reserving slabs. Nobody should cut stone from them. The cutting file comes from a digital template taken after the cabinets are fitted and packed level, because walls in older Mandurah homes are rarely square and a 5mm error becomes a permanent shadow line you look at every day. If your numbers put you within about 200mm of a slab length, that is a measure question rather than a maths question, and it is worth having someone look before you commit to a colour.
Sizing questions
How many square metres of stone does a typical Mandurah kitchen need?
How big is a stone slab, and how many will I need?
How do I measure my benchtop properly with a tape?
How much wastage should I allow on a stone benchtop?
What is the sizing mistake that costs the most in Mandurah kitchens?
Can I order stone from my own measurements?
Next: which material suits your house, what happens on install day, and what the warranty covers.
Check your slab count before you order
Send the measurements you just took and we reply within one business day with the slab count, where the join would land and a firm price range.
We measure it properly, for free
Digital template, compliant materials and a fixed written quote across Mandurah, Halls Head, Greenfields, Dawesville, Falcon and Pinjarra.