A refrigerator has to fit the kitchen it stands in and the way the household shops. Most fit trouble shows up at the door, the counter line, or the tightest turn on the delivery route, not in the cooling itself.
Measure the opening and the swing
Measure the space the refrigerator will stand in, from wall to wall and from the floor to the lowest point of any cabinet above. Note where the door hinges and which way it must open. Check that the door can open fully with the adjacent wall or cabinet in place. A door that cannot open all the way makes the shelves hard to reach, and the household ends up changing its habits to suit the cabinet.
Check the depth at the counter line
Standard depth and counter-depth models sit differently against the cabinet face. Look at where the door handles will land against the counter edge. Then allow room behind and at the sides for air to move, using the clearances on the installation sheet for the model you pick. Tight placement can keep the coils from breathing, so check this before the unit is delivered.
Match the freezer share to the shopping
Think about how the household buys food. A household that shops every week needs different space from one that buys in bulk or cooks from the freezer. Compare the fresh-food space and the freezer space against what actually goes into each. Look at the door bins and the shelf layout, and ask whether the shelves can be moved to fit tall containers. If the model makes ice, decide now where its water line will run.
Plan the delivery route
Walk the route from the door to the kitchen. Measure the tightest doorway, hallway turn, and stair landing, and note the height of any step. A unit that does not fit the route will not reach the kitchen, whatever its size on paper.
Keep the age in the plan
Age is a planning input, not a verdict. When the household's shopping habits or the kitchen layout change, check the refrigerator against the new plan. The appliance ranking gives typical service life for the major appliances, so you can place the planning point on the calendar.