Average Width of a Microwave | Standard Sizes By Type

Most countertop microwaves are 18–25 inches wide, while over-the-range units run about 30 inches to fit standard cabinets.

If you’re replacing an old microwave or planning a kitchen layout, width matters more than any other dimension. A microwave that’s too wide for its spot is a return trip you don’t want. The average width of a microwave depends almost entirely on which type you’re shopping for — countertop, over-the-range, or built-in — and each category follows its own standard range.

What Is The Average Width For Each Microwave Type?

Countertop models are the most common and the most varied. Compact units run about 15–18 inches wide, while standard and large countertop microwaves fall between 21–25 inches. Maytag, for instance, lists small countertop units at 15–18 inches and standard or large ones at 21–25 inches.

Over-the-range microwaves are a different story. These units replace your range hood and must line up with the cooking surface below. Maytag states most are around 30 inches wide to match standard 30-inch ranges and cabinets. Some compact over-the-range units come in near 24 inches, but 30 inches is the norm.

Built-in microwaves follow cabinet dimensions rather than appliance norms. Standard built-in widths are 24, 27, or 30 inches, designed to slide into cabinets built to those openings.

Countertop Sizes By Brand

Brand spec sheets confirm the same pattern. KitchenAid lists its countertop microwaves at 21–25 inches wide. Whether you buy a budget model or a premium unit, the exterior footprint stays within that band for full-size options.

A few things shift the number:

• Compact models (0.7–0.9 cu. ft.): roughly 15–18 inches wide — good for dorms, offices, or tight counters.
• Mid-size models (1.0–1.4 cu. ft.): about 18–21 inches wide — the most flexible for standard kitchens.
• Full-size models (1.5–2.2 cu. ft.): 21–25 inches wide — the most common family choice.

Cavity size doesn’t dictate exterior width. A 1.6-cubic-foot unit from one brand can be wider than a 2.0-cubic-foot from another because insulation, turntable size, and vent placement differ.

How To Measure Your Microwave Space Correctly

Home Depot’s guidance is straightforward: measure horizontally across the widest exterior sides of the microwave. That means left to right across the body, not diagonally and not including loose handles if you’re matching a tight opening — though handles do need clearance.

Three measurements matter when you’re shopping:

• Width — the left-to-right exterior dimension, which most people check first.
• Depth — front to back; countertop clearance and cabinet depth both depend on this.
• Height — top to bottom; over-the-range units need clearance between the range and the upper cabinet.

The most common mistake is confusing interior capacity with exterior width. A larger cubic-foot rating doesn’t guarantee a wider body. The second frequent error is measuring only the unit itself and ignoring door swing clearance or the cabinet niche requirements for built-in and over-the-range models. For those types, manufacturer specs include minimum trim-kit and opening dimensions you must match — a unit wider than the opening simply won’t fit without cabinet work.

If you’re working with a tighter counter and need something that fits a specific slot, our roundup of 18-inch wide microwaves covers compact models that still handle everyday reheating.

Over-The-Range And Built-In Fit Rules

Over-the-range microwaves are tied to your range’s width. Guidance from manufacturers ties these units to standard cabinet and range openings, which is why nearly all measure about 30 inches. If your range is 30 inches — the near-universal standard — a 30-inch microwave aligns perfectly above it. A 24-inch compact over-the-range unit exists for narrower setups, but it’s the exception.

Built-in models demand even more attention to the niche. A 27-inch built-in goes into a 27-inch cabinet opening; a 30-inch needs a 30-inch opening. There’s no “close enough” with these — the trim kit must match both the microwave and the cabinet exactly. Before buying any built-in, measure the opening’s width, height, and depth, then compare against the manufacturer’s installation sheet, not just the product title.

Measure your space before you shop, and write down the width, depth, and height in inches. That single step prevents most returns. And remember that your counter’s width isn’t the only constraint — leave a few inches of breathing room on each side for ventilation and door clearance.