We compiled the cabinet-cutout specs for every built-in steam oven. Here's what won't fit.

Finding 1: Width is the easy part. Height is the trap.

Every one of the 21 built-ins in this study fits inside a standard 30-inch wall-oven opening (about 28½ inches of cutout width) — so width almost never decides it. The height does. Required cutout heights run from 17.31" to 25.81" — a 8.5-inch spread. That means a steam oven that dropped perfectly into your neighbor's cabinet can be physically impossible to fit in yours, even though both are "30-inch" ovens. If you're replacing an existing wall oven, the height of your cabinet opening is the first number to check — not the width.

Finding 2: Most built-in steam ovens can't just be plugged in.

Here's the cost nobody quotes you: of the 21 models, 13 require a hardwired connection — a fixed conduit run to a junction box that needs a licensed electrician — while only 6 use a cord and plug. If your cabinetry doesn't already have the right circuit and connection where the oven goes, budget for an electrician on top of the sticker price. It's the single most common surprise in built-in steam-oven installs.

Finding 3: The door needs room too.

Cutout dimensions tell you if the box fits. They don't tell you if you can open it. The deepest door-swing in our data belongs to the Thermador Masterpiece 30" Steam Convection Oven MEDS301BS, which projects about 45.88" into the room when open. In a galley kitchen with a run of cabinets or an island close behind, that's the difference between a smooth install and a door that bangs into your peninsula.

How we compiled this

Every figure comes verbatim from the manufacturer's own installation or specification document — cabinet cutout width, height and depth, plus door-open depth and electrical connection — and each is cited on the model's page. We only publish numbers we can quote from an official source; where a manufacturer doesn't publish a value, we leave it blank rather than estimate. No other site compiles this.