Why does my microwave make a loud humming or buzzing noise?

A light humming sound is normal while a microwave is operating, but a loud or unusual buzz is not something to ignore. Check the appliance externally first, because unstable placement, an empty cavity or a trapped accessory can make the noise seem worse.

1. Confirm that the microwave is sitting level on its non-slip feet and not touching nearby objects. Expected result: stable placement reduces vibration noise.
2. Check that the turntable and ring are seated correctly and nothing is rubbing. Expected result: the noise should not change when the tray turns.
3. Compare the sound during low-power and normal-power operation. Expected result: some change in hum is normal, but grinding or rattling is not.
4. Try the microwave with a microwave-safe item inside, not empty. Expected result: the oven should sound steadier with a proper load.
5. Stop using the microwave if the buzzing becomes loud, metallic or is joined by burning smells, sparking or loss of heating. Do not try to tighten or replace internal components yourself.

If the issue remains unresolved, or safe use is uncertain, contact the retailer or store where the product was purchased.