A magnetized watch usually runs fast, often by many minutes a day, and the change comes on suddenly. If your mechanical watch was keeping good time and now gains several minutes daily, magnetism is the most likely cause. You can test for it with a compass: hold the watch close and see whether the needle moves. The fix is quick and inexpensive. A watchmaker removes the magnetism with a demagnetizer in a few seconds, and no harm is done.
It is one of the most common watch problems and one of the least serious. This guide explains how to recognize it, where it comes from and how to avoid it.
Why magnetism affects a watch
The heart of a mechanical watch is the balance spring, or hairspring: a very fine coil of metal that expands and contracts several times a second and sets the rate of the watch.
In a traditional movement that spring is made of a steel alloy that can become magnetized. When it does, its coils stick to one another. The spring is effectively shortened, the balance swings in a smaller arc and faster, and the watch gains time. In a strong field the coils can cling so tightly that the watch stops.
Other steel parts of the movement can be magnetized too, but the hairspring is the part that changes the timekeeping.
Is my watch magnetized? The signs
- It suddenly runs fast. This is the classic sign. A gain of anything from a few minutes to more than an hour a day is typical.
- The change was abrupt. A watch that needs a service drifts slowly over months or years. A magnetized watch changes from one day to the next.
- It behaves erratically, gaining different amounts on different days.
- It stops, in severe cases, and may restart when shaken.
A magnetized watch does not usually run slow. If yours is losing time, look for another cause.
The compass test
You need a simple needle compass. A compass app on a phone is not reliable for this.
- Lay the compass flat on a table, well away from phones, speakers and anything metal, and let the needle settle.
- Bring the watch slowly toward the compass, then move it around it.
- Watch the needle.
If the needle swings to follow the watch, the watch is magnetized. If it barely moves, it is probably not. Any steel object will disturb a compass slightly at very close range, so look for a clear, definite movement.
A watchmaker can confirm it in seconds with a timing machine, which also shows how the watch is running.
What magnetizes a watch
Magnets are everywhere in daily life, and the strength of a magnetic field falls away quickly with distance. Trouble comes from close contact. The usual sources:
- Magnetic clasps on handbags, tablet covers, phone cases and laptop sleeves. These are among the most common culprits, because the watch rests right against them.
- Speakers and headphones, which contain strong magnets.
- Laptops and tablets, which have magnets in the lid and speakers. Resting your wrist on a closed laptop is a classic way to magnetize a watch.
- Phones and wireless chargers.
- Induction cooktops.
- Refrigerator doors and other magnetic seals.
- Medical equipment, especially MRI scanners, which have extremely strong fields. Never take a watch into an MRI room.
The practical advice is simple: do not leave a watch lying on or against electronics, speakers or bags with magnetic clasps. A few inches of distance is usually enough.
How it is fixed
A watchmaker uses a demagnetizer: a device that produces an alternating magnetic field. The watch is passed through it and drawn slowly away, which scrambles and removes the magnetism. It takes a few seconds, does not require opening the watch, and costs very little. Many watchmakers and jewelers do it while you wait.
Inexpensive demagnetizers are sold for home use, and they work when used correctly. Used wrongly, they can leave a watch more magnetized than before, so if you are not sure of the method, a visit to a watchmaker is the easier course.
Once demagnetized, the watch should return to its normal rate at once. If it does not, magnetism was not the cause, or not the only one, and the watch may need regulating or a service. Our guide to how often to service a watch explains the other reasons a watch drifts.
Does magnetism damage a watch?
No. Magnetism changes how the watch runs while it is present and leaves no lasting harm. Once removed, the movement is as it was. The only real risk is the indirect one of relying on a watch that is telling the wrong time.
Which watches resist magnetism
Watchmakers have attacked the problem in two ways.
Shielding
The traditional solution is a soft-iron inner case around the movement, which diverts magnetic fields away from it. This is how the classic antimagnetic watches of the 1950s worked, including the Rolex Milgauss, named for its resistance to 1,000 gauss, and the IWC Ingenieur. The limits are that it adds thickness and rules out a see-through case back.
Non-magnetic parts
The modern solution is to make the sensitive parts from materials that cannot be magnetized.
- Silicon balance springs are unaffected by magnetism. Omega, Tudor, Breguet, Patek Philippe and many others now use them.
- Rolex uses its own alloy, Parachrom, for its blue hairspring, and a silicon spring it calls Syloxi in some movements.
- Omega's Master Chronometer watches go furthest: the movement is built from non-ferrous materials throughout and each watch is tested by the Swiss institute METAS to resist fields of 15,000 gauss. Most current Seamaster and Speedmaster models carry this certification, as do Tudor's newest Master Chronometer watches.
For comparison, the international standard that allows a watch to be called antimagnetic requires resistance to a field of only about 60 gauss.
If you work around strong magnetic fields, or simply never want to think about the problem, a Master Chronometer is the practical answer. Our guide to chronometer certification explains what the tests cover.
What about quartz watches?
A quartz watch can be affected while it sits in a strong field: the small motor that drives the hands may stall or lose steps. Once it is moved away it usually runs normally again, though the time will need resetting. Quartz watches do not stay magnetized in the way mechanical ones do.
When a pre-owned watch runs fast
If you buy a pre-owned watch and it gains several minutes a day, do not assume the worst. Watches are often magnetized in transit or in storage near electronics, and a demagnetizer may be all it needs. Every watch we sell is checked by our specialist before it ships, timing included; if a watch you receive from us is not keeping time as it should, tell us. Our pre-owned watch checklist lists what else to look at.
Frequently asked questions
How do I know if my watch is magnetized?
The usual sign is that it suddenly starts running fast, often by several minutes a day. A compass needle that moves when the watch is brought close confirms it.
Can I demagnetize a watch myself?
Yes, with a demagnetizer made for watches, if you follow the method carefully. A watchmaker can do it in seconds for very little.
Does magnetism damage a watch permanently?
No. Once the magnetism is removed, the watch runs as before.
Can a phone magnetize a watch?
It can, if the watch rests against it or against a magnetic case or wireless charger for long. Keeping a little distance avoids the problem.
Which watches are antimagnetic?
Watches with silicon balance springs resist magnetism well. Omega and Tudor Master Chronometer watches are tested to 15,000 gauss.
My watch runs slow. Is it magnetized?
Probably not. Magnetism almost always makes a watch run fast. A watch that loses time more likely needs regulating or servicing.
