What you need to do before you start
Replacing an over-the-range microwave is a job you can do yourself if you are comfortable on a ladder and working with basic tools. The process takes two to four hours and involves disconnecting the old unit, removing it from the wall, and installing the new one in its place. You will need a helper to support the weight — most over-the-range microwaves weigh between 60 and 100 pounds — and you should turn off power at the breaker before you touch anything electrical.
The hardest part is usually not the removal but the fit. Over-the-range microwaves are designed to sit in a specific space above your stove, and the mounting brackets, ductwork, and electrical outlet may not line up perfectly with a new unit. Before you buy a replacement, measure the opening, check the depth of your cabinets, and confirm that the new microwave's dimensions match what you have. If the new unit is wider or deeper than the old one, you may need to adjust the cabinet opening or hire someone to do it.
Check whether your current microwave is hardwired (connected directly to the electrical system) or plugged into an outlet. Hardwired units require an electrician to disconnect and reconnect safely. Plugged units you can handle yourself. Look behind or above the microwave to see the connection — if you see a cord, it is plugged in; if you see wires going into the wall, it is hardwired.
Key Takeaways
- Turn off power at the breaker before you disconnect anything, whether the microwave is hardwired or plugged in.
- Measure the opening and compare it to the new microwave's dimensions before you buy, because cabinet modifications are expensive if the unit does not fit.
- You will need a second person to support the weight while you remove the old unit and install the new one.
- Hardwired microwaves require an electrician to disconnect and reconnect; plugged units you can do yourself with basic tools.
- The mounting brackets and ductwork from the old unit may not work with the new one, so check compatibility before installation day.
Measuring and preparing the space
Start by measuring the width, height, and depth of the opening where your microwave sits. Measure from the inside of the cabinet frame, not from the trim. Write down the exact dimensions. Then measure the depth of your cabinet — from the front edge to the back wall — because some over-the-range microwaves are deeper than others and will not fit if your cabinet is shallow.
Next, look at the new microwave's specifications sheet and compare every dimension. Pay special attention to the depth, because that is where most fit problems happen. If the new unit is deeper than the old one and your cabinet is tight, you will need to move the cabinet back or remove part of it. If the new unit is wider, you may need to adjust the cabinet opening. These modifications cost $200 to $500 if you hire someone, so get the measurements right before you commit.
Check the location of the ductwork — the pipe that carries steam and smoke outside. If your old microwave vents to the outside, the ductwork is already in place. If it recirculates (pulls air through a filter and back into the kitchen), you may have more flexibility. Look at where the new microwave's ductwork connection is located and confirm it lines up with what you have. If it does not, you will need to reroute the ductwork, which is a job for someone with HVAC experience.
Disconnecting power and removing the old unit
Turn off the breaker that controls your microwave. If you are not sure which one it is, turn off the breaker and test the microwave to confirm it has no power. Do not skip this step, even if the microwave is plugged in — there are live wires inside the unit that can cause serious injury.
If the microwave is plugged into an outlet, unplug it. If it is hardwired, you will see wires connected to a terminal block or junction box inside the cabinet above the microwave. Do not touch these wires yourself — call a licensed electrician to disconnect them. Hardwired units are connected to the main electrical panel, and working with them without training is dangerous.
Once power is off, remove the mounting bolts that hold the microwave to the cabinet frame. These are usually located on the sides or top of the unit, inside the cabinet. You may need to remove the trim or filler panels to reach them. Use a socket wrench or adjustable wrench to loosen and remove these bolts. Have your helper stand on a sturdy ladder and support the microwave from below while you remove the bolts, because the unit will fall if you do not.
Carefully slide the microwave toward you and lower it onto a sturdy cart or table. Do not try to carry it down the ladder — the weight and awkward shape make it straightforward to drop. Once it is on a stable surface, disconnect any remaining wires or ducts that are still attached.
Preparing the new microwave and mounting brackets
Unpack the new microwave and lay it on a clean, flat surface. Check the box for mounting brackets, hardware, and an installation manual. Read the manual before you start — different manufacturers use different bracket systems, and you need to know which bolts go where.
Most over-the-range microwaves come with new mounting brackets. Remove the old brackets from the cabinet frame using a wrench or socket set. Clean the area where the brackets were mounted, because dust and grease buildup can prevent a tight fit. If the new brackets are a different size or shape, you may need to drill new holes in the cabinet frame. Use a drill bit that matches the bolt size specified in the manual, and drill slowly to avoid splitting the wood.
Install the new mounting brackets according to the manual. Make sure they are level and find — use a level tool to check. Tighten all bolts firmly, but do not over-tighten, because you can crack the cabinet frame. The brackets need to support 60 to 100 pounds, so they must be solid.
Installing the new microwave
With your helper on the ladder, carefully lift the new microwave and position it so the mounting holes line up with the brackets. This is the hardest part because the unit is heavy and awkward. Go slowly and have your helper guide it into place while you watch from the side to make sure nothing is hitting the cabinet or ductwork.
Once the microwave is in position, insert the mounting bolts through the holes in the unit and into the brackets. Tighten them by hand first, then use a wrench to tighten them firmly. Check that the microwave is level and sits flush against the cabinet frame. If it is tilted or sitting crooked, loosen the bolts, adjust the position, and tighten again.
Connect the ductwork to the microwave's exhaust outlet. If you are using the old ductwork, make sure the connection is tight and sealed with duct tape or a duct clamp. If the ductwork does not line up, you will need to reroute it or install an adapter — check the manual to see what adapters are available.
Reconnecting power and testing
If the microwave is plugged in, plug it into the outlet. If it is hardwired, call the electrician back to reconnect the wires to the terminal block. Do not attempt this yourself.
Turn the breaker back on. Press the power button on the microwave to confirm it turns on. Set it to run for 30 seconds on high power and listen for the fan and the magnetron (the part that generates heat). If the microwave runs without sparking or making unusual noises, the installation is complete.
Test the ductwork by turning on the exhaust fan and checking that air is moving outside. If you have a recirculating microwave, the filter should be clean and in place. Run the microwave for a few minutes while cooking something to confirm the exhaust is working and steam is being pulled away from the stovetop.
Common problems and how to fix them
If the microwave does not fit in the opening, the cabinet may be too shallow or the opening may be too narrow. Measure again to confirm. If the depth is the problem, you can remove the back panel of the cabinet to gain a few inches, or you can have a carpenter adjust the cabinet frame. If the width is the problem, you may need to remove or adjust the trim around the opening.
If the ductwork does not line up, you have two options: reroute the ductwork to match the new microwave's outlet, or install an adapter that connects the old ductwork to the new outlet. Adapters are available from the microwave manufacturer or from HVAC supply stores. Rerouting ductwork is more work but gives you a cleaner installation.
If the microwave is not level after installation, loosen the mounting bolts slightly and use shims (thin wedges) under the brackets to adjust the angle. Tighten the bolts again once it is level. A microwave that sits crooked will not close properly and may not seal steam inside.
If the exhaust fan is not working, check that the ductwork is not kinked or blocked. Look inside the cabinet above the microwave to confirm the ductwork is connected and not crushed. If the ductwork is fine, the fan motor may be defective — contact the manufacturer for a replacement.
When to call a professional
Call an electrician if your microwave is hardwired or if you are not confident working with electrical connections. Hardwired microwaves are connected to the main panel, and mistakes can cause fire or electrocution.
Call a carpenter or cabinet maker if the new microwave does not fit in the opening and you need to modify the cabinet frame or opening. Cutting into cabinet frames requires precision, and a mistake can weaken the structure or damage the cabinets.
Call an HVAC technician if you need to reroute ductwork or if the exhaust is not working after installation. Ductwork that is not properly sealed or routed can cause moisture buildup in the walls and attic.
Frequently Asked Questions
Can I install an over-the-range microwave myself if I have never done this before?
Yes, if the new microwave fits in the existing opening and is plugged in rather than hardwired. The job requires a helper, a ladder, and basic tools like a wrench and level. If you need to modify the cabinet, reroute ductwork, or disconnect hardwired electrical connections, hire a professional for those parts.
What if the new microwave is smaller than the opening?
You can install filler panels or trim around the edges to close the gap. Most microwave manufacturers sell trim kits designed for this purpose. Measure the gap and order the correct size before installation day.
Do I need to turn off the breaker if the microwave is plugged in?
Yes. Even though the microwave is plugged in, there are live wires inside the unit that can cause injury. Turning off the breaker ensures the power is completely off before you disconnect anything.
How long does installation usually take?
Two to four hours if everything fits and you are not modifying the cabinet or ductwork. If you need to adjust the opening, reroute ductwork, or wait for an electrician, add several hours or a full day.
What should I do with the old microwave?
Microwaves contain parts that should not go in the trash. Take it to an electronics recycling center or a scrap metal facility. Some retailers that sell microwaves will haul away the old one for a fee when they deliver the new one.