Dishwasher Sizes: 18-Inch vs 24-Inch (and How to Measure Your Opening)
Almost every built-in dishwasher is one of two widths: 24 inches (the standard) or 18 inches (the compact). Height and depth barely move between them. So the real questions are which width your cabinets are cut for, and whether your “standard” opening is actually standard — because in older kitchens, it often isn’t.
The two standard sizes
Width is the only dimension that meaningfully changes. Both sizes share roughly the same height and depth so they slot under a standard 36″ counter.
| 24″ (standard) | 18″ (compact) | |
|---|---|---|
| Opening width | 24″ | 18″ |
| Height | 33½–34½″ | 32½–34½″ |
| Depth | ~24″ | ~22–24″ |
| Place settings | 12–16 | 8–10 |
Rough opening vs the dishwasher itself
This is the detail that trips people up. A “24-inch” dishwasher is usually about 23½–23¾″ wide — the 24″ refers to the cabinet opening it’s designed to slide into, leaving a sliver of room on each side. So when a listing says 24″, read it as the opening, not the appliance.
In older kitchens, measure — don’t assume
A “standard” 24″ opening is only standard if the kitchen was built for it. New tile or thicker flooring can lift the floor and shrink the height; a counter replacement can change the underside clearance; and hand-built cabinets are rarely a clean 24″. Measure width, height (floor to counter underside), and depth before you order.
Who should choose 18-inch
An 18″ dishwasher makes sense in a small kitchen, a galley, a bar area, or a one-to-two-person household. You trade away roughly four place settings — the difference between running it daily and every other day. One thing to weigh: 24″ is what most buyers expect, so an 18″ unit can be a small negative at resale unless the kitchen genuinely can’t take a 24″.
Height, leveling, and the door
Both sizes have adjustable feet, usually spanning 33½–34½″, so the top clears the underside of the counter while the unit sits on the floor. Two things to confirm: the unit’s minimum height fits under your counter after any new flooring, and the door has room to drop fully open without hitting an island or an opposite cabinet in a galley.
Compare the models: browse dishwasher dimensions, or read the master measuring guide for the three-point method that applies to any opening.
Frequently asked
What is the standard dishwasher size?
Will an 18-inch dishwasher fit a 24-inch opening?
What is the rough opening for a dishwasher?
Are all dishwashers the same depth?
Measured from official ENERGY STAR data + manufacturer spec sheets · Last verified June 2026