Do Microwaves Block Wifi?
Quick answer
A running microwave can slow or drop WiFi on the 2.4 GHz band, because microwave ovens heat food at about 2.45 GHz, inside the same frequency range. A tiny amount of energy escapes even from a safe, working oven, and it is enough to drown out a weak WiFi signal nearby. Connecting to your router's 5 GHz band avoids the problem.
If your video call stutters every time someone reheats coffee, the microwave is probably to blame. It isn’t really “blocking” WiFi; it is drowning it out.
Why microwaves interfere with WiFi
Microwave ovens heat food with radio waves at about 2.45 GHz. WiFi’s 2.4 GHz band covers roughly 2.4 to 2.5 GHz, so the two overlap.
The metal box and the mesh in the door keep almost all of that energy inside. Almost all is not quite all, though. A microwave uses around 1,000 watts of radio energy to cook, while a WiFi router transmits at a tiny fraction of a watt. Even a very small leak from the oven can be stronger than the WiFi signal reaching a device across the room, so the device loses packets until the oven stops.
This leakage is normal and doesn’t mean the microwave is unsafe. The FDA sets a strict limit on how much energy a microwave oven can leak over its lifetime, far below the level known to harm people. A small leak that disrupts WiFi is still well within it.
How to stop microwave WiFi interference
- Use the 5 GHz band. Most routers sold in the last decade are dual-band. Connect your device to the 5 GHz network (it often has “5G” in its name) and the microwave can no longer interfere with it. 5 GHz has a shorter range and passes through walls less well, so it works best within a room or two of the router.
- Move the router away from the kitchen, or at least so the microwave isn’t between the router and where you use your devices.
- Change the 2.4 GHz channel. Trying a different channel (1, 6 or 11 are the non-overlapping ones) in your router settings sometimes helps, though it won’t remove the problem entirely because the microwave’s emissions spread across much of the band.
- Use a wired connection for a TV or desktop computer near the kitchen.
Other things that interfere with 2.4 GHz WiFi
- Older cordless phones and baby monitors that use 2.4 GHz
- Bluetooth devices (usually only a minor effect)
- Neighbouring WiFi networks on the same or overlapping channels
- Thick walls, metal, mirrors and large fish tanks between the router and your device
Should I worry that my microwave is leaking?
A WiFi drop alone is not a sign of a dangerous leak. You may have seen a “test” where you put a phone inside the closed (switched-off) microwave and call it. That isn’t a reliable safety test. Phones mostly use different frequencies from the oven, and the door shielding is designed to contain the oven’s own 2.45 GHz energy while it is running. Real leakage checks are done with a calibrated meter on a running oven.
Do have the microwave checked or replaced if the door is damaged, bent or doesn’t close properly, if the hinges or seals are broken, or if the oven keeps running with the door open. Don’t try to repair the door or shielding yourself.
Why do microwaves and WiFi share 2.4 GHz?
The 2.4 GHz range is one of the industrial, scientific and medical (ISM) bands. Microwave ovens, which aren’t communications devices, were allowed to operate there. Because equipment in that band has to tolerate interference, regulators later opened it to unlicensed low-power devices such as WiFi, Bluetooth and cordless phones. That made it cheap for everyone to use, at the cost of sharing it with a lot of other equipment, including your microwave.