How to Measure Cubic Feet of Microwave | Interior Math

Measure the interior width, depth, and height in inches, then divide the product by 1,728 to get the cubic feet.

Figuring out the cubic feet of a microwave is a simple interior measurement, not a guess about the outside shell. You need a tape measure, about two minutes, and a calculator. The number matters because it tells you the actual cooking volume — whether that casserole dish fits or whether the machine is better suited to reheating coffee.

Why Cubic Feet Measures the Inside, Not the Outside

The cubic feet rating describes the empty cooking cavity, never the exterior shell. A bulky microwave with thick insulation and a big handle can take up plenty of counter space yet offer a modest interior. That is why the exterior dimensions tell you about fit, while the cubic feet tell you about cooking capacity.

When you need to verify a model’s true size, the published specification is the most reliable route. Check the user manual or the product spec sheet for “capacity” or “volume” — most manufacturers list cubic feet directly. That figure is measured at the factory, so it accounts for the whole cavity in a way a hand measurement with a tape can never quite match.

The Simple Measurement Formula

Measuring a microwave yourself is straightforward. Open the door and measure the empty interior from wall to wall.

• Width — measure across the inside, left to right, in inches.
• Depth — measure from the back wall to the front edge of the interior floor, in inches.
• Height — measure from the floor of the cavity to the ceiling, in inches.

Multiply the three numbers together, then divide the result by 1,728 (the number of cubic inches in one cubic foot). So a cavity measuring 16 inches wide by 14 inches deep by 10 inches high works out to 2,240 cubic inches, which equals about 1.3 cubic feet.

What the Numbers Actually Look Like

Microwave capacities cluster into a few familiar ranges. Compact models usually fall between 0.5 and 0.8 cu. ft., mid-sized models between 0.8 and 1.4 cu. ft., and large models from 1.4 up to over 2.0 cu. ft. A standard countertop unit runs about 18–24 inches wide, 10–18 inches high, and 18–22 inches deep, while over-the-range models typically span 29–30 inches wide.

A 1.2 cu. ft. capacity is common for a microwave drawer, and plenty of countertop models land right in that neighborhood as well. Once you know the cubic feet you need, the next step is finding a model that fits your counters and your cooking routine — our roundup of the best 1-cubic-foot microwaves sorts through the top options in that mid-sized sweet spot.

Why the Manual’s Number Beats Your Tape Measure

A hand measurement works fine for a ballpark figure, but it misses details. The interior of a microwave rarely forms a perfect rectangle — the turntable hump, the rack supports, the door latch, even the bulb housing carve space out of the cavity. Your manual’s published capacity already accounts for all of that, which is why it is the better reference when precision matters, like when you are comparing two models side by side.

The measurement method also assumes an empty cavity. Turntables, glass trays, and racks sit inside the space but are not part of the cooking volume itself, so they do not factor into the cubic feet number. When the exact capacity is critical for fitting a specific dish, skip the tape measure and trust the spec sheet.

If your manual is long gone, search the model number online — the capacity is usually on the manufacturer’s spec page. Failing that, the quick interior calculation above gives you a close working number that is plenty accurate for deciding whether a new appliance fits your kitchen.