Microwave Opening Size Guide (Over-the-Range & Built-In + Fit Tips)

Standard Microwave Opening Sizes

Most microwaves fall into two categories: Over-the-Range (OTR) and Built-In.

Over-the-Range Microwave (OTR):

Width: 29 7/8" to 30"

Height: 16" to 17"

Depth: 15" to 18"

Cabinet space above the microwave typically requires:

Height: 12" to 15"

Built-In Microwave:

Width: 24", 27", or 30"

Height: 17" to 22"

Depth: 20" to 24"

⚠️ Even a difference of 1/4 inch can cause installation issues or require cabinet modifications.

Microwave opening sizes can vary depending on the brand and model. Always verify the appliance specifications before purchasing.

Many homeowners run into problems after delivery because the microwave doesn’t match the available space.

To avoid this, measure your cabinet opening carefully before buying.

How to Measure a Microwave Opening

1. Measure the width of the cabinet opening.

2. Measure the height of the opening.

3. Measure the depth from the back wall to the front edge.

4. For OTR microwaves, also measure the space between cabinets above the range.

Use exact measurements (example: 29.75 inches). Do not round up.

Avoid Installation Problems

Many homeowners discover installation issues after the microwave is delivered because the cabinet opening does not match the appliance dimensions.

Measuring carefully before purchasing helps prevent installation delays and extra modifications.

Check Microwave Fit Before You Buy

Don’t Buy the Wrong Size Microwave

Even small measurement differences can lead to costly installation issues, trim kit problems, or returns.

Use Appliance Fit Check to instantly compare your microwave with your space before you buy.

✔ Avoid trim kit and cabinet issues

✔ Ensure proper fit for built-in or over-the-range installs

✔ Used by real installers