An over-the-range microwave is almost always 30 in wide, 16–17 in high, and 15–17 in deep, and it mounts with its top edge 66 in from the floor — which leaves 13–18 in of clearance above the cooktop. Countertop models are smaller and far looser on the rules: 18–25 in wide depending on capacity, needing only a few inches of vent space. Nail that mount height and everything else falls into place.
Front view
30 in width
16–17 in high
Side view
cooktop
15–17 in deep
13–18 in
66 in to top
Every microwave size in one table
Capacity is measured in cubic feet, and it’s the number that actually drives the exterior size. A 0.7 cu ft compact swallows a mug and a small plate; a 2.2 cu ft unit takes a full dinner platter without you spinning it sideways. Here is how the common types compare.
| Microwave type | Width | Depth | Height | Capacity |
|---|---|---|---|---|
| Countertop — compact | 18–20 in | 14–15 in | 11–12 in | 0.7–0.9 cu ft |
| Countertop — mid-size | 20–22 in | 15–18 in | 12–13 in | 1.0–1.4 cu ft |
| Countertop — large | 23–25 in | 18–20 in | 13–14 in | 1.5–2.2 cu ft |
| Over-the-range | 29–30 in | 15–17 in | 16–17 in | 1.6–2.1 cu ft |
| Built-in / trim kit | 24–30 in | 20–24 in | 17–19 in | 1.2–2.2 cu ft |
What to Look For When Buying a Microwave
Size fits the spot; wattage and type decide how well it actually cooks and vents.
- Wattage — 1,000 W or more cooks evenly; under 800 W is slow and uneven
- Type — countertop is cheapest and movable; over-the-range doubles as a vent; built-in looks seamless
- Venting (OTR) — for an over-the-range unit, 300+ CFM venting actually clears steam and smoke
- Interior capacity — 1.5 cu ft or more fits a large dinner plate or casserole dish
- Sensor cooking — a humidity sensor stops the guesswork on reheats and popcorn
| Type | Typical US price | Best for |
|---|---|---|
| Countertop | $60–250 | Renters, extra kitchens |
| Over-the-range | $200–600 | Saves counter, vents |
| Built-in / drawer | $400–1,200 | Seamless, custom kitchens |
Prices are typical US ranges and vary by brand, size, and features — ballparks, not quotes.
Notice the depth jump: countertop and over-the-range units are shallow, but a built-in with its trim kit runs deep because the whole cabinet is finished around it. That depth is what trips people up when they try to drop a built-in into a spot sized for a range hood, which is why capacity alone never tells you whether a unit will physically land.
How much clearance do you need above the cooktop?
This is the number that gets ignored until the drywall is already patched. Most over-the-range microwaves are UL-listed to mount with 13–18 in between the bottom of the microwave and the cooktop surface, but that band is a floor, not a target — check the model’s spec sheet, because the exact minimum shifts with the vent design and whether you run gas or electric below.
Two numbers do the real work here: the 13 in hard minimum most brands print in the manual, and the 66 in floor-to-top height that keeps the door reachable. Hit both and the microwave clears a tall stockpot on the front burner without roasting its own underside or the plastic on your spatula. The industry default is a taller 30 in from the cooktop to the bottom of a plain range hood, but an OTR combo is engineered to sit lower and still handle the heat.
The mounting height that ties it together is 66 in from the floor to the top of the microwave. That puts the controls within reach for most adults and keeps the vent above the tallest pots. If your cooktop sits at a nonstandard height, or you’re pairing this with a slide-in range, cross-check the burner height against our range and oven dimensions before you drill the mounting template.
Will a countertop microwave actually fit your space?
Width is the easy part. Depth and door swing are what kill a countertop install. Standard counters are 24 in deep, and most upper cabinets hang 18 in above the counter — a large 14 in-tall microwave eats most of that gap and blocks the outlet behind it. Leave at least 3 in of clearance on the top, back, and sides for the vents, or the unit runs hot and the fan screams.
One more depth trap: manufacturers list microwave depth two ways, door closed and door open. The open-door figure can hit 30 in or more, so if a wall, a fridge, or a full-height pantry sits beside the spot, measure the swing, not just the box. A door that only opens 80% is a daily annoyance you’ll feel every single time.
If the microwave is landing on an island, the depth matters even more because there’s no wall to stop the door — walk the walkway math in our kitchen island size and clearance guide first. And because a microwave shares the run with everything else, sanity-check your surface height and reach against the standard kitchen counter height and depth before you commit the spot.
Microwave width at a glance
Compact
18–20 in
Mid-size
20–22 in
Large
23–25 in
Over-range
30 in
Built-in
24–30 in
Over-the-range vs built-in: which mounts where
An over-the-range unit replaces a 30 in cabinet directly above the cooktop, hangs from a wall bracket, and vents either back through the wall, up through the roof, or simply recirculates through a charcoal filter. A built-in slides into a tall cabinet or a wall next to a wall oven and needs a matching trim kit — usually 27 in or 30 in — to fill the opening cleanly. That trim kit is not optional; it’s what provides the airflow channel.
A third mount worth knowing is the microwave drawer. It slides into a base cabinet or an island below the counter, opens like a drawer instead of a swinging door, and runs 24 or 30 in wide to match standard cabinet boxes — but it’s deep, usually 23–24 in, so it needs a full-depth base cabinet behind it. Drawer units cost more and sit low, which some cooks love and tall cooks don’t; either way they free the wall above the cooktop for a dedicated vent hood.
Planning a full appliance wall? The microwave rarely lives alone. Map its cabinet against the neighbors using our refrigerator dimensions, and if the run continues down the wall, the dishwasher size and cutout numbers keep the whole layout on a consistent 24 in depth line.
The mistakes people actually make
- Filling a 33 in gap with a 30 in OTR. The microwave won’t stretch. You need filler strips or a different cabinet layout — measure the opening, not the microwave.
- Forgetting the outlet. An over-the-range unit needs a receptacle in the cabinet above it, not on the wall behind the cooktop. If it isn’t there, that’s an electrician’s call before install day.
- Door swing into a backsplash. A countertop microwave shoved into a corner can’t open its door fully — leave the hinge side clear.
- Mounting too high for the cook. The 66 in rule is a starting point; if the primary cook is under 5 ft 4 in, reaching a hot dish over a live burner is a real hazard. Drop it slightly if clearance allows.
- Assuming it vents outside. Many OTR installs recirculate, which does little for steam and grease. Confirm the duct path before you count on it.
Sorting the rest of the room after the kitchen? The full Roomly size guides cover everything from appliances to the laundry pair in our washer and dryer dimensions breakdown.
Frequently Asked Questions
Yes, as long as you leave roughly 3 in of clearance on the top, back, and sides for the vents. A large 14 in-tall unit fits under standard 18 in-high uppers, but it will block the outlet and most of the working light — measure the gap first.
The standard is 66 in from the floor to the top of the microwave, which leaves 13–18 in of clearance above the cooktop. Always confirm the minimum on your specific model’s spec sheet, since it varies by brand and vent design.
Built-in and drawer models use a trim kit, most commonly 27 in or 30 in wide. The rough opening follows the trim kit spec, not the microwave itself — the kit fills the gap and creates the airflow channel, so buy the matching kit for your exact model.
They can, but many are installed to recirculate air through a charcoal filter instead of ducting outdoors. Recirculating does little for steam and grease, so if real ventilation matters to you, confirm there’s a duct path to the exterior before you buy.