How Wide Is a Standard Microwave? | Width by Type

A standard countertop microwave is usually 21–25 inches wide, while over-the-range and built-in models commonly measure 30 inches wide to match standard US cabinetry.

Figuring out a microwave’s width means first knowing which type you need. Countertop, over-the-range, and built-in models each cluster around different sizes. Measure your available space before you shop—grab a tape measure rather than relying on your old appliance’s label—and you will land on the right fit without the headache of a return.

Countertop Microwave Widths

Countertop microwaves come in three loose width tiers. Small units for dorm rooms or offices run 15–19 inches wide. Standard household models—the ones that sit on a kitchen counter—measure 21–25 inches wide. Larger, full-size countertop ovens push into the 24–30-inch range and usually hold 1.6 cubic feet or more. Before you buy, measure the counter space itself and leave at least 1 inch of open space behind the unit for ventilation.

Over-the-Range and Built-In Widths

Over-the-range microwaves share a common width: about 30 inches, matching standard 30-inch cabinetry. Maytag notes that most over-the-range models are around 30 inches wide, 17 inches high, and 15 to 18 inches deep with the door closed. Built-in microwaves also center on 30-inch cabinet niches, though exact dimensions depend on the model’s cutout specifications. If you are replacing an existing unit, measure the cabinet opening—do not trust the old microwave’s sticker. Over-the-range and built-in units are not interchangeable with countertop models because of mounting hardware, venting, and cutout requirements.

How to Measure for a Microwave

Grab a tape measure and follow these steps for a clean install. For a countertop microwave, measure the counter’s depth, height clearance between shelves or cabinets, and width on the spot where it will sit. For an over-the-range replacement, measure the cabinet cutout width, height, and depth, and check the manufacturer’s required ventilation clearances before buying. The specific manual for whatever model you choose overrides all general guidance—check it before you peel the tape off the box.

Common Measuring Mistakes to Skip

Measuring only the old microwave instead of the actual cabinet or counter opening is the most frequent error. Door swing clearance, wall proximity, and ventilation gaps are easy to overlook, and each one can make a microwave that fits on paper unusable. External dimensions and internal capacity are two separate numbers: a bigger cubic-foot rating does not mean the unit is wider. And remember—”standard” is not one single width. A 21–25-inch countertop model is standard for the counter; a 30-inch over-the-range model is standard for the cabinet. Choose the type first, then measure.

If your cabinet or counter space is narrower than the standard range, a compact model might be the smart solution. Our roundup of the best 16-inch-wide microwaves covers reliable picks that fit tighter spots without sacrificing performance.