A dishwasher is sized by the household and the kitchen, not by the catalog page. Start with how your home actually uses the machine. A household that cooks every night loads it differently from one that eats out most evenings. Work through three questions before you compare any model.
How many people, how often
Count the people who eat at home on a normal day and on a busy one. Note how many place settings, serving pieces, and pans go into the machine after a typical meal. A household that cooks often and washes large pots by hand is more likely to need the deep lower rack and adjustable tines than one that eats mostly simple meals.
What fits the opening
Measure the cabinet opening, the height under the countertop, and the depth to the back wall. Most dishwashers are built for a standard opening, but kitchens are not always standard. Check the feet and the leveling range. Confirm that the countertop overhang leaves room for the door to open fully.
Water, drain, and the wait
Check what is already under the sink. You need a hot water supply that can reach the unit and a drain connection that can take the discharge. Ask how far the hot water has to travel from the water heater to the kitchen. A long run means a longer wait before the machine gets hot water on a cycle.
Test the load
Before you commit, picture a typical dinner going into the machine. If the pots fit the lower rack and the plates fit the upper, the size is likely right. If the pans crowd every shelf, look at a deeper model, or plan to hand wash the largest items.
For planning when to look at the machine next, the dishwasher page in the index gives the typical service life and when to plan: Dishwasher: typical service life and when to plan.