The key points
- Measure the tightest usable opening, including the finished floor.
- Product size and required cavity size are separate checks.
- Have services and full door movement assessed for the exact model.
Start with a clear measurement record
Measure the unobstructed width at the front and farther inside the opening. Record height from the finished floor to the underside of the benchtop at several points. Note the smallest measurement rather than choosing the most generous one. Photograph the opening with the measurements written beside it, and identify any trim, brackets or lip that reduces access. If new flooring is planned, use its intended finished level. Do not force an old dishwasher out to obtain a measurement; its safe removal and disconnection should form part of the installer’s assessment when access is restricted.
Separate appliance dimensions from cavity requirements
An appliance’s external size and its required opening are different entries on a specification sheet. AEG’s FFE83800PM page publishes product dimensions and height adjustment separately. Fisher & Paykel’s tall dishwasher planning guide distinguishes product dimensions from cavity dimensions and directs installers to the installation instructions. Those examples show why adding a guessed gap to a product width is unreliable. Record both sets of figures for the exact model you are considering, including any handle projection or panel arrangement. There is no single clearance allowance that should be applied to every dishwasher or every underbench installation.
Look behind and in front of the machine
Measure usable depth with existing pipes and fittings in view, rather than stopping at the nominal back wall. Show the installer the water connection, waste connection, power point and the route into adjacent cabinets. A rear obstruction may affect whether the appliance can sit at the intended front line. In front, mark where the door reaches when fully open and where you would stand to unload it. Check drawers and cupboard doors beside the opening as well. A machine that can be pushed into the recess may still be frustrating if a neighbouring handle prevents the dishwasher door opening properly.
Turn measurements into a fit decision
Send your record, photographs and the full model number to a suitable qualified installer before finalising the purchase. Ask them to identify any cabinet alteration, service change, moisture protection or special mounting requirement. Planning guides help shortlist a model, but the installation document governs the actual job. For a Value House listing, also confirm included panels and fittings, along with the stated condition and warranty. Keep the approved drawing with your order details so the appliance and installation discussions refer to the same version. This simple record is especially useful when a cabinetmaker, delivery team and installer are involved at different times.
Before you buy
- Record width, height and usable depth in several positions.
- Photograph services, floor transitions and surrounding doors.
- Find the model-specific cavity and installation drawings.
- Confirm the fit and required work with a qualified installer.
Sources & further reading
Prepared with AI assistance using the manufacturer and Australian guidance linked below. Check the exact model’s documentation when planning a purchase or installation.
