The Trap of the "Standard" Dishwasher
Over my years on the appliance floor, I have seen countless customers walk in assuming a dishwasher is just a universal box. They pick out a beautiful stainless steel tub model, arrange delivery, and then call me in a panic three days later when the installer tells them it will not fit. Assuming all dishwashers are the exact same size is one of the most frustrating mistakes you can make during a kitchen update.
There is an ideal standard opening size in the appliance industry. If the cutout under your counter is 34 inches tall, 24 inches wide, and 24 inches deep, you are in great shape. Almost any standard dishwasher on the market will slide right into that space with enough room to breathe for the water lines and the power cord.
The nightmare scenarios happen when your opening is even a fraction off those standard dimensions. If your kitchen has seen a few remodels, you might have layers of new flooring installed directly over old tile or hardwood. That immediately eats into your vertical clearance, and a standard dishwasher will wedge against the countertop and refuse to go in.
Width can be just as tricky. If the opening is narrower than 24 inches, the immediate question is exactly how much narrower. You must be as precise as possible when doing this measurement, especially if it is less than 24. If you have 23 and 5/8 inches, you might be able to use certain European brands that are built slightly slimmer. If you only have 18 inches, you are looking at specialized compact units. There are still options for these tight spaces, but there are far fewer choices and they are generally more expensive.
The cavity itself is only half the battle. You also need to factor in the space around the machine. If your dishwasher sits in a corner, you have to ensure a protruding handle will not block your adjacent cabinet drawers from opening. If the unit is installed around the corner from a sink, you may need longer fill and drain hoses than the ones that come with the units. On top of that, the plumbing itself has to be right. The air gap or high loop installation needs to be done properly to prevent dirty sink water from flowing back into your clean dishes.
A significant part of why I began this project is because of precisely these kinds of problems. They are entirely preventable. Just measure. Not sure about your measuring? Have someone else do it to double check. Punch those into my Dishwasher Fit Calculator: https://tmdspecreview.com/tools/dishwasher-calculator/ - I'm happy to make some recommendations that will fit.