What a worktop height and appliance niche checker looks at
A worktop does not sit at a single fixed height. It sits on top of a stack: the cabinet's adjustable legs, the carcass (the structural box of the cabinet, built from board) on top of them, and the worktop material itself resting on that. Change the thickness of any one part and the height the worktop finishes at moves with it. An appliance that has to slide into the gap under the worktop, such as a built-under oven, dishwasher or fridge, needs that gap, known as the niche, to fall inside a specific range.
That range comes from the appliance's own installation instructions. A checker that takes your carcass height, leg height and worktop thickness, works out the finished niche, and compares it against the range printed in the appliance instructions is doing arithmetic you would otherwise do with a tape measure and a calculator, standing in the showroom or the kitchen itself.
How the height is built up
Each part of the stack is set by a different decision, often made by a different person at a different stage of the order.
Carcass height
The carcass is the box the doors, drawers and worktop all attach to. Its height is fixed by the range you choose, and it is one of the figures worth checking against the maker's own specification page before you order, because two ranges that look alike on the showroom floor can carry different carcass heights.
Leg height
Cabinet legs are adjustable, within the limits the leg itself allows, which is what lets a fitter level a run of cabinets across an uneven floor. Adjusting the legs to level the run also changes the finished worktop height slightly, and that adjustment has to be accounted for before an appliance niche is measured.
Worktop thickness
Worktop thickness depends on the material. A laminate worktop and a solid stone worktop are not the same thickness, and swapping one for the other partway through a project changes the finished height and the niche below it. The differences between materials, and what drives the thickness of each, are set out on the worktops compared page.
Why the appliance niche range matters
An appliance is not designed to fit any gap of roughly the right size. Its instructions set a minimum and a maximum niche height, because the appliance needs enough clearance to sit level and be secured, but not so much that its door catches the worktop above or leaves a gap a hand could reach into. A few millimetres either way, at either end of that range, is the difference between an appliance that slides in cleanly and one that has to be forced, packed out, or sent back.
The instructions that carry this figure come with the appliance, so it is worth reading them before you order the cabinet run. Where the appliance and the cabinet maker's own literature give different niche figures for what looks like the same job, the appliance manufacturer's instructions are the ones that govern, because they are written for that specific model.
Where height mismatches usually start
- Ordering the appliance after the cabinets: a niche built to a guess, then checked against the real instructions once the appliance is chosen, is the most common way a gap ends up the wrong size.
- Levelling the legs without re-checking the niche: levelling a run of cabinets across a sloping floor changes the finished height at each point along the run, and a niche measured before levelling is not the niche the appliance will actually meet.
- Switching worktop material partway through a project: moving from a laminate worktop to a stone one, or the other way round, changes the thickness sitting on top of the carcass and shifts every niche below it.
- Reading the wrong dimension from the appliance instructions: some manuals give the niche as a range, others as a single figure with a separate tolerance, and mixing the two up produces a niche that looks right on paper but is not.
- Assuming plinth height and leg height are the same thing: the plinth (the panel that covers the legs at floor level) is a cosmetic cover, and adjusting it does nothing to the height the worktop sits at.
Checking your own numbers
Working through the stack by hand means measuring the carcass height from the maker's specification, reading the leg height as set by your fitter once the run is level, checking the worktop thickness for the material you have chosen, and reading the niche range from the appliance's own installation instructions, then adding and comparing. The worktop height and appliance niche checker takes those same four figures and returns the finished worktop height, whether the appliance fits, and the adjustment needed if it does not.
The result is only as good as the figures you put in. If the carcass height is read from a range other than the one you are actually ordering, or the appliance niche range is copied from the wrong model in a manual that covers several, the checker will return an answer that looks precise and is wrong. It is worth re-checking the source of each figure, particularly the appliance instructions, before treating the result as final.
Where to go next
The wider guide to kitchen heights and sizes covers the 600mm module that sets cabinet widths alongside worktop height and appliance niches, and is worth reading before you place an order that fixes any of these dimensions. Trade terms used here, and others you will meet across a specification sheet, are explained in the kitchen glossary. Where an appliance has already been supplied and does not fit the niche it was sold against, the guide to your rights when buying a kitchen sets out what the Consumer Rights Act gives you and where to take a dispute the supplier will not resolve.