Replacing a Microwave: What to Check Before You Buy

Measure the opening first

Before you shop, measure the space where the microwave will sit. Note the width, height, and depth of the opening, including any clearance for the plug, the door, and the handles. The old unit may look like an exact fit, but the next model can be larger or smaller even when the capacity rating is the same.

For countertop placement, also measure from the countertop to the cabinet above and leave room for airflow. For over-the-range, built-in, and drawer models, the cabinet opening matters more than the exterior width. If you are unsure how to take these measurements, see how to measure for a microwave and review standard microwave sizes before comparing models.

Match the mounting type

The most important replacement decision is mounting type. A countertop microwave sits on a surface and can be moved. An over-the-range microwave hangs under a cabinet and usually includes a cooktop light and vent. A built-in microwave fits into a cabinet opening with a trim kit, and a drawer microwave slides out from under a counter or cabinet.

If you replace the old unit with the same mounting type, the installation is usually simpler. Changing mounting types can require new cabinetry, a different outlet location, or new venting. If you are considering a switch, compare the practical trade-offs before buying, including how the microwave will fit into the space and what it will replace.

Check electrical requirements

Most home microwaves need a dedicated circuit with the right outlet type and voltage, but the exact requirement depends on the model. Check the nameplate and the manufacturer installation instructions before ordering. Manufacturer sites, including GE Appliances, publish appliance manuals and installation guidance that list these details.

At minimum, confirm four things: the outlet location, the outlet type, the circuit rating, and whether the unit is hardwired or plug-in. If the existing setup does not match, plan to have a qualified electrician make the change. See microwave electrical requirements and microwave hardwired vs plug-in for more detail.

Check venting and ductwork

For an over-the-range replacement, venting is often the deciding factor. Identify whether the existing installation vents to the outside or simply recirculates the air through a filter. If the old unit was recirculating, a new vented model will need a duct route to the outside. If the old unit was vented, confirm that the replacement connects to the same duct opening and that the damper moves freely.

Also check the available duct direction and the blower type. Some units can be configured for top or rear exhaust, but not every model offers both. Review the venting types and ventilation CFM guidance to match the replacement to your kitchen setup.

Match the trim kit

If you are replacing a built-in microwave, the trim kit is not universal. Each trim kit is designed for a specific microwave model or model family. A new microwave will usually require a new trim kit unless the manufacturer states that the old one is compatible. Check the trim kit model number, not just the width of the opening.

See microwave trim kit compatibility before you choose. For a built-in replacement, the final fit depends on the exact cabinet opening, the microwave dimensions, and the trim kit matched to that model.

Check door swing and clearance

Open the old door and note which way it swings. If the replacement has the opposite swing, you may need to reverse the door, or the door may not open fully in the available space. Check the clearance on the hinge side and make sure the door can open without hitting a wall, cabinet, or handle.

Some models allow the door swing to be reversed; others do not. If this matters for your kitchen, confirm the option before buying. A model that fits the opening may still be the wrong choice if the door cannot open comfortably.

Plan for the old unit

Before the new microwave arrives, plan how to remove and dispose of the old one. Unplug it and remove it carefully. If the unit is built-in or over-the-range, follow the manufacturer removal instructions to avoid damaging the cabinet or the electrical connection.

Check local options for electronics donation and recycling before putting the old product out. The EPA notes that recycling electronics conserves natural resources and avoids pollution. For more on safe removal and disposal, see how to recycle an old microwave.

Cook safely after installation

Once the microwave is in place, follow the FDA's food safety advice for microwave cooking. Cover food, stir, and rotate for even cooking. If the unit has no turntable, rotate the dish by hand once or twice during cooking. Always allow standing time, which completes the cooking, before checking the internal temperature with a food thermometer.

Matching size, mounting, electrical, and venting gets the new unit installed correctly. Using it the right way from the start helps it work safely in your kitchen.

What to pick for your use

Questions

Can I replace my over-the-range microwave with a countertop model?

You can, but a countertop model will not vent the cooktop. You will need to address the cabinet opening, the outlet location, and the venting that the old over-the-range unit provided. If you remove the over-the-range unit, install a range hood or another venting solution.

Do I need the same trim kit for a new built-in microwave?

Not necessarily. Trim kits are usually matched to a specific microwave model. Confirm compatibility with the new model before ordering, because the old trim kit may not fit the new unit even if the opening size looks the same.

Can I install a vented over-the-range microwave if there is no duct?

Only if you add ductwork. Without a duct route, choose a model that can be used in recirculating mode with a charcoal filter. Check the venting options in the installation instructions before you buy.

What if the old microwave has a different plug or circuit?

Do not modify the plug to force it into an outlet. Check the new microwave's electrical requirements and compare them with the existing circuit. If they do not match, have a qualified electrician update the circuit.

Is it safe to use an old microwave that still heats but has a damaged door?

No. A damaged door can affect the safety interlocks. The FDA regulates radiation-emitting products, and a microwave with a damaged door should be replaced, not used.