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To demagnetize a watch, place it on an electric watch demagnetizer, switch the unit on, then slowly lift the watch straight away to at least 12 inches (30 cm) before switching it off. That gradual withdrawal through a fading alternating field scrambles the magnetized steel parts back to neutral. Check the result with a compass, repeat once if needed, and the watch should return to its normal rate.
Magnetism is the most common reason a mechanical watch suddenly runs fast, and it is one of the few watch problems you can fix safely at home. Here is how to test for it, how to fix it and how to stop it happening again.
Why watches get magnetized
A mechanical watch keeps time with a balance wheel and a hairspring that coils and uncoils several times a second. In most watches, the hairspring is a thin steel alloy. When it is exposed to a strong magnetic field, its coils can stick together slightly, which shortens the effective spring and makes the watch run fast, sometimes by minutes a day.
Everyday sources include:
- phone speakers and magnetic phone mounts;
- magnetic laptop and tablet covers, and laptop lids;
- bag and purse clasps;
- speakers, headphones and earbuds cases;
- induction cooktops and some kitchen tools;
- airport security wands and handheld scanners;
- some watch winder motors, at very close range (see are watch winders bad).
Quartz watches are mostly unaffected in daily life: their stepping motor can be disturbed while near a strong magnet, but they usually recover when it is removed.
How to tell if your watch is magnetized
The symptom
The giveaway is a sudden change. A watch that kept time within seconds a day starts gaining several minutes a day, or behaves erratically. Our guide to an automatic watch running fast covers the other causes, but sudden, large gains point to magnetism first.
The compass test
- Put a simple magnetic compass on a table, away from metal and electronics.
- Let the needle settle.
- Slowly pass the watch over or beside the compass, with the dial facing the compass.
- If the needle swings or follows the watch, parts of the movement are magnetized.
A steel case or bracelet can itself move a needle slightly, so look for a clear, repeatable deflection when the movement (the center of the watch) passes closest.
The phone app test
Most smartphones have a magnetometer. Free magnetometer apps show the field strength in microteslas. Note the reading with no watch nearby, then hold the watch against the phone's sensor. A large jump suggests magnetism. It is a rough guide, not a precise measurement.
Timing apps
Watch-timing apps that listen to the ticking through the phone's microphone can show the rate and beat. A magnetized watch often shows a large positive rate and a messy trace. They confirm the problem but do not identify the cause.
How to demagnetize a watch at home: step by step
You need a basic electric watch demagnetizer. They are small boxes, usually blue or black, with a push button or switch, and they are sold inexpensively online and in watchmaker supply shops.
- Check the voltage. Use a unit built for US 110-120 V outlets, or a dual-voltage unit. Read its instructions.
- Remove the watch from your wrist and keep it on its strap or bracelet.
- Place the watch flat on the center of the demagnetizer, dial up.
- Press and hold the button (or switch the unit on). The unit hums.
- Slowly lift the watch straight away from the demagnetizer, over 2 to 3 seconds, to at least 12 inches (30 cm).
- Release the button only once the watch is well away. Switching off while the watch is still on the unit can leave it magnetized.
- Check with the compass. If the needle still moves, repeat once, trying the watch on its side.
- Check the rate over the next day against your phone's clock.
Do not leave the unit running for long periods; most are meant for short bursts.
Can you demagnetize a watch without a demagnetizer?
Not reliably. Demagnetizing needs an alternating field that fades smoothly, which is exactly what the tool provides. Rubbing or waving a magnet near the watch risks making it worse. Phone apps that claim to demagnetize a watch cannot generate the field needed.
If you do not want to buy a tool, take the watch to a watchmaker or a jeweler with a watch bench. Demagnetizing takes them seconds, and many do it while you wait.
Choosing a demagnetizer
Watch demagnetizers are simple devices, and most of the inexpensive units sold online look alike. A few things are worth checking:
- Voltage and plug: a US-plug 110-120 V unit, or a dual-voltage one.
- Size of the pad: a pad large enough to lay the whole watch flat makes the process easier.
- Momentary switch: a button you hold, rather than a switch you might forget, avoids overheating.
- Instructions: look for a unit that explains distance and timing; follow them over any general advice, including ours.
Most of these units are sold by small, little-known brands, so treat them as basic tools. If the watch is valuable, a watchmaker's demagnetizer and their experience are a safer bet.
One example that meets the voltage point is TICFROG's unit, sold on Amazon with a US plug and a compass for the test in step 7. Like the others, it comes from a small brand, so follow its own instructions.
What about quartz watches and smartwatches?
A quartz watch's timekeeping comes from a crystal oscillator, so magnetism does not change its rate the way it does a mechanical hairspring. A strong magnet held right against a quartz watch can stall its stepping motor temporarily, but it usually restarts when the magnet is removed. Do not use a demagnetizer on a smartwatch; it is unnecessary, and electronics are best kept out of strong alternating fields.
When to see a watchmaker instead
- The watch is still fast after two demagnetizing attempts.
- The watch has stopped, not just sped up; see automatic watch stopped working.
- The rate is erratic, or the watch was also dropped.
- It is due for a service anyway; see how often to service an automatic watch.
- It is a valuable or vintage watch and you would rather not risk it.
Demagnetizing does not open the case, so it does not affect water resistance.
How to stop your watch getting magnetized
- Keep it off phones and laptops. Do not rest your wrist on a laptop's palm rest near the speakers, and do not put the watch on top of a phone.
- Watch out for magnetic clasps on bags, phone wallets and cases.
- Store watches away from speakers, TVs and smart speakers.
- Keep winders apart. Leave a little space between a winder and other electronics.
- Consider antimagnetic movements. The international standard ISO 764 defines antimagnetic watches as resisting a field of 4,800 A/m (about 60 gauss). Some modern movements go far beyond that by using non-steel hairsprings, such as Tissot's Nivachron balance spring, which is designed to resist magnetism. See our guide to automatic watches under 1000 for examples.
Common mistakes
- Assuming the watch is broken. A sudden gain of minutes a day is usually magnetism, not damage.
- Switching the demagnetizer off with the watch still on it.
- Holding the watch on the unit too long. A short pass is enough.
- Trying magnets or home remedies.
- Re-magnetizing it immediately by putting it back on the laptop.
FAQ
How do I know if my watch is magnetized?
The classic sign is a mechanical watch that suddenly runs fast, often by minutes a day, after keeping good time. To check, hold the watch near a simple compass: if the needle moves as the watch passes, parts of the movement are magnetized. Phone magnetometer apps can give a rough reading too.
How do you demagnetize a watch at home?
With an inexpensive electric demagnetizer. Switch it on, hold the watch flat on or just above it, then slowly lift the watch straight away to about 12 inches (30 cm) or more before switching the unit off. Check with a compass and repeat once if needed.
Can you demagnetize a watch without a demagnetizer?
Not reliably. Demagnetizing needs an alternating magnetic field that fades gradually, which a demagnetizer provides. Waving magnets or using household tricks can make it worse. If you do not want to buy a tool, a watchmaker can demagnetize a watch quickly, often while you wait.
Can a phone demagnetize a watch?
No. A phone can help you detect magnetism with a magnetometer app, and phone speakers and magnetic cases are a common cause of magnetized watches. Apps that claim to demagnetize a watch cannot produce the field needed.
Does magnetism damage a watch permanently?
Usually not. Magnetism changes how the hairspring behaves, so the watch runs fast, but demagnetizing restores normal timekeeping in most cases. If a watch still runs badly after being demagnetized, it may need regulation or a service.