A standard over-the-range microwave is about 30 inches wide, while countertop microwaves typically run 21 to 25 inches wide.
A 30-inch microwave slides into the same slot as the range hood it replaces. That single number is why over-the-range models cluster so tightly around 30 inches while countertop units scatter across a four-inch spread. Width is the one dimension you cannot work around — height can clear a cabinet, depth can leave a small gap, but a microwave that is too wide simply does not fit.
Here is what those widths look like in practice, how built-in sizes differ, and the measurement mistake that sends people back to the store with a box under one arm.
Average Microwave Width by Type
Countertop microwaves span roughly 21 to 25 inches wide. Over-the-range microwaves sit at about 30 inches, with compact over-the-range units around 24 inches. Built-in models line up with cabinet openings of 24, 27, or 30 inches.
Those ranges come from Maytag’s sizing guide, which lays out typical dimensions by category rather than a single universal figure. The reason is simple: each type solves a different space problem. A countertop model only has to fit under your upper cabinets. An over-the-range model has to match the range below it and the hood vent above it. A built-in model has to match a cabinet cutout that a builder already framed.
| Microwave Type | Typical Width | Typical Height and Depth |
|---|---|---|
| Countertop | 21–25 in. | 12–15 in. high; 16–20 in. deep |
| Over-the-range | About 30 in. | About 17 in. high; 15–18 in. deep |
| Compact over-the-range | About 24 in. | Narrower cabinet fit; shorter body |
| Built-in (standard cabinet) | 24, 27, or 30 in. | Matches cabinet cutout; trim kit closes gaps |
| Built-in (trim kit match) | Cutout width, plus trim | Trim kit bridges appliance to opening |
| Interior cavity (any type) | Smaller than exterior | Roughly 0.8–1.2 cu. ft. on most models |
| Door-swing clearance | Add wall gap | One manual calls for 6 in. on the left side |
Why a 30-Inch Microwave Is Not Universal
Model dimensions vary enough that measuring beats assuming, every time. Maytag’s guide is explicit that actual sizes differ between models, so the appliance and the opening both need a tape measure before you buy.
The mismatch that causes the most returns is confusing overall width with cutout width. A microwave described as 30 inches wide is 30 inches across its exterior — the interior cavity is far smaller, usually somewhere between 0.8 and 1.2 cubic feet on household models. If you are replacing a built-in unit, the number that matters is the cabinet opening, not the old microwave’s outer shell.
Clearance is the other silent failure. One manufacturer’s installation instructions ask for at least 6 inches between the wall and the microwave on the left side so the door swings open the whole way. A unit that measures perfectly can still fight you every time you reach for a plate of leftovers.
If your kitchen only has about 15 inches of open counter under the cabinets, a full-size countertop model will not clear the door swing — a tighter footprint is the fix, and our tested roundup of 15-inch-wide microwaves covers the models that actually fit that gap.
How To Measure Your Space Before You Buy
Measure the opening first, then match the appliance to it — never the reverse. Your installation manual and the cabinet or range opening are the two documents that decide whether a microwave fits.
- Measure the opening width at its narrowest point — for over-the-range, between the cabinets above the range.
- Measure height and depth of the same opening, noting any cabinet lip or trim that narrows the space.
- Check side clearance against the manual’s door-swing requirement — 6 inches on the left is a common figure, and your model may differ.
- Compare against the model’s actual spec sheet, not the category average, since a “30-inch” label can hide an inch of variation.
- Confirm the cutout width if you are buying built-in, and check whether a trim kit is needed to bridge the gap.
KitchenAid’s measuring guidance makes the same point from the other direction: the appliance has to answer to the cabinet, so the cutout is the starting measurement, not the finishing one. When the numbers line up on paper, they line up in the kitchen.
FAQs
Are all over-the-range microwaves 30 inches wide?
No. Most are, but compact over-the-range models run about 24 inches wide. Because the unit has to match both the range below it and the vent above it, width is the one dimension with the least flexibility. Measure your opening rather than trusting the category, since individual models vary.
Does a 1.5 cubic foot microwave fit the same space as a 1.0 cubic foot one?
Not necessarily. Interior capacity describes the cavity, not the exterior shell. Two microwaves with the same cubic footage can have different outer widths, and a larger-cavity unit is usually wider and deeper. Check the exterior dimensions, not just the capacity rating, before assuming it will slide into the same spot.
How much clearance does a microwave door need?
It depends on the model and the hinge side. Some installation manuals ask for at least 6 inches between the wall and the microwave on the left so the door opens fully. A tight corner or a cabinet lip on the hinge side can block the swing even when the width measures fine.
References & Sources
- Maytag. “Microwave Sizes: A Guide to Common Dimensions” Supports typical width ranges by microwave type and the caution that dimensions vary by model.
- KitchenAid. “Microwave Sizes: How to Measure a Microwave” Supports the cutout-first measuring approach and built-in sizing against cabinet openings.
- Midea. “Dimension of Microwave” Supports general exterior-versus-interior dimension guidance and clearance considerations.
