How to Demagnetize Your Watch (and How to Know You Need To)
Your watch ran fine for months. Now it gains a few minutes a day, and nothing about your routine changed. Before you pay for a service, rule out the cheap culprit: magnetism.
Mechanical and automatic watches are tiny machines, and they do not love magnets. The good news is that the fix takes about a minute and costs very little.
What magnetism does to a watch
Inside an automatic movement, a balance wheel swings back and forth on a thin spiral spring called the hairspring. The coils breathe in and out to keep time. If the spring becomes magnetized, neighboring coils can cling to each other. The spring effectively gets shorter, the balance swings faster, and the watch runs fast. Not by seconds. Often by minutes a day.
Some magnetized watches also run erratically, or stop and start for no clear reason.
What magnetizes a watch
You rarely need a big magnet. Everyday objects do it:
- Phone and tablet speakers, and magnetic tablet covers
- Laptop speakers and the area around a trackpad
- Magnetic clasps on bags, wallets and purses
- Headphones and bluetooth speakers
- Fridge doors and magnetic knife strips
- Induction cooktops and some kitchen appliances
Resting your watch on a phone at night is a classic way to do it.
Step 1: Test it with a compass
You do not need special gear to check.
- Use a plain compass, or a compass app on a phone. Keep the phone's speaker side away from the watch afterward.
- Hold the watch close to the compass and slowly move it around.
- Watch the needle. If it stays pointed north, the watch is fine. If the needle swings or follows the watch as you rotate it, the watch is magnetized.
This test is a good indicator, not a lab measurement. A watch can run fast from magnetism and still give a weak compass reaction. If the symptoms fit and the compass test is borderline, treat it as magnetized and demagnetize it.
Step 2: Demagnetize it
A handheld watch demagnetizer is a small, inexpensive device sold online, and watchmakers use the same principle in bench tools. It produces an alternating field that scrambles the magnetism in the hairspring.
- Take the watch off and keep it away from other electronics.
- Press the demagnetizer button and hold the watch against the device. Follow the instructions that came with yours.
- While the device is still on, slowly pull the watch straight away, at least a foot or so, before releasing the button. Pulling away slowly matters. Switching the device off while the watch is close can re-magnetize it.
- Test with the compass again. If the needle now stays steady, you are done.
If the watch is valuable and you are nervous about doing it yourself, ask a local watchmaker. They usually do it in a minute.
Step 3: Check timing over a few days
Set the watch against a reliable time source, wear it normally for two or three days and compare. If it is still off by a lot after demagnetizing, the problem is not magnetism. Maybe the movement needs regulation or a service. That is a good moment to see a watchmaker rather than keep guessing.
How to keep it from happening again
- Keep watches off phones, tablets, speakers and magnetic bag closures.
- Do not store a watch in a drawer next to a speaker or a laptop.
- Know that most standard automatic watches do not have strong antimagnetic protection. Check a brand's own stated resistance rather than assuming.
A note on our watches
The Manx runs on a Miyota Cal. 9122 automatic movement. Like most standard automatics, treat it with the same common sense: keep it away from strong magnets, and use the compass test if it starts running oddly. We do not claim an antimagnetic rating on the Manx. If you own one and the timing looks wrong, message us and we will help you work out whether it is magnetism or something else.
For more watch basics, see the Mercier Prototype Journal.
FAQ
How do I know if my watch is magnetized?
It usually runs fast, often by minutes a day. Hold a compass near it: if the needle follows the watch or swings, it is probably magnetized.
Can I demagnetize a watch at home?
Yes. A handheld watch demagnetizer works in about a minute. Hold the watch to it while it is on, then pull the watch away slowly before switching it off.
What if the watch is still fast after demagnetizing?
Then magnetism is not the cause. The movement probably needs regulation or a service from a watchmaker.