A magnetised watch is a mechanical watch whose hairspring has picked up enough magnetism for its coils to stick together, which shortens the spring's effective length and makes the watch run fast, often by minutes a day, and sometimes stop altogether. It is the single most common fault a watchmaker sees on a modern Rolex, Patek Philippe or Audemars Piguet, it is caused by everyday objects such as bag clasps, phone cases and speakers, and it is fixed in seconds with a demagnetiser and no disassembly. This guide covers the symptoms, how to test a watch at home, what magnetises it, how it is fixed and what it costs, which current calibres are built to resist magnetism, the Rolex Milgauss that was designed for it, and how to keep a watch away from magnets in the first place. The Milgauss collection lists the reference most owners think of when the subject comes up.
Last reviewed on September 25, 2026 by Filip Biczak. Prices are dated observations, not quotes.
Symptoms of a magnetised watch
| Symptom | What you notice | Why it happens |
|---|---|---|
| Running fast | Gains from a minute to many minutes a day, suddenly, on a watch that kept good time before | Magnetised hairspring coils stick, shortening the spring and speeding the balance |
| Erratic rate | Fast some days, near correct on others | Coils stick and release as the watch moves |
| Stopping | Watch stops with power in the mainspring, restarts when shaken | Heavy magnetisation locks coils together or magnetises steel parts of the train |
| Running slow | Less common; loses time | Magnetised escapement parts drag on each other |
| Short power reserve | Runs down faster than the calibre's stated reserve | Magnetised mainspring coils or barrel components add friction |
The pattern to recognise is sudden onset. A watch that has gained two seconds a day for three years and then gains three minutes a day from one morning has almost certainly met a magnet; a watch that has drifted slowly over years needs a service, not a demagnetiser. The Rolex watch care and service page covers the service side of that distinction.
How to test whether a watch is magnetised
The simplest test uses a compass, either a real one or a compass app on a phone laid flat and left to settle. Bring the watch slowly toward the compass from a few centimetres away; if the needle or the on-screen needle swings as the watch approaches, the watch is carrying a magnetic field. Repeat from each side of the case, since the hairspring sits at one edge of the movement. A clean, unmagnetised watch will not move a compass needle at all. The second test is rate: set the watch against a reference time and check it after 24 hours; a gain of a minute or more on a Rolex, Patek Philippe or Audemars Piguet that is inside its service interval points to magnetism before anything else. A watchmaker confirms with a timing machine, which shows a magnetised watch as a wildly fast rate with a large, unstable beat error, and can demonstrate the fix by demagnetising and re-timing in front of you.
What magnetises a watch?
- Bag and case clasps. The magnetic closures on handbags, laptop sleeves and tablet cases are the commonest source; a watch on the wrist that holds the bag meets the clasp dozens of times a day.
- Phone and tablet cases. Folio cases with magnetic closures and magnetic mounting rings on the back of phones sit against the wrist when the phone is held.
- Speakers and headphones. Any loudspeaker, including the ones in laptops and wireless earbuds cases, contains a permanent magnet.
- Refrigerator doors and magnetic tools. The seal on a fridge door is a strip magnet at wrist height; magnetic screwdriver tips and knife blocks are strong at close range.
- Medical and security equipment. An MRI scanner will magnetise and can damage a watch; airport security scanners and hand wands generally do not.
- Motors and induction hobs. Electric motors, power tools and induction cooktops produce fields strong enough to affect a watch held close.
The field needed is small. The Swiss standard for an "antimagnetic" watch, ISO 764, requires it to survive 4,800 amperes per metre, about 60 gauss, and a fridge magnet or a bag clasp can exceed that at the surface. A watch without an antimagnetic hairspring can be magnetised by a field it meets for a fraction of a second.
How to fix a magnetised watch and what it costs
Demagnetisation is a two-second procedure. The watch is passed slowly over a demagnetiser, a coil that produces an alternating magnetic field, and drawn away while the field is on; the alternating field scrambles the magnetic alignment in the hairspring and steel parts and leaves them neutral. The case does not need to be opened, nothing is adjusted and the watch is then re-checked on a timing machine to confirm the rate has returned to normal. Any competent watchmaker or a brand service centre does it while you wait and most charge little or nothing for it; it is the cheapest repair in watchmaking. If the rate does not return to normal after demagnetisation, the problem is something else, most often a hairspring that was physically bent by a shock or a movement that is due for service, and the watchmaker will say so. Do not try to demagnetise a watch with a household magnet or a phone app that claims to do it; a static magnet makes things worse and an app does nothing. Our authentication process includes a timing-machine check that catches magnetism before a watch is dispatched.
Which watches resist magnetism? Rolex, Patek Philippe and Audemars Piguet compared
| Brand and calibre | Antimagnetic component | Introduced | Watches |
|---|---|---|---|
| Rolex 3235, 3255, 3285, 4131 | Blue Parachrom hairspring in a niobium-zirconium alloy, Chronergy escapement in nickel-phosphorus; largely insensitive to magnetic fields | Parachrom 2000, blue Parachrom 2005, Chronergy 2015 | Datejust 41, Submariner, GMT-Master II, Explorer II, Daytona 126500, Day-Date 40 |
| Rolex 2236 and 7140 | Syloxi silicon hairspring, non-magnetic | 2014 in the Datejust Pearlmaster; 7140 in the 2023 Perpetual 1908 | Ladies' Datejust and Pearlmaster, Perpetual 1908 |
| Rolex Milgauss 116400 | Parachrom hairspring plus a soft-iron inner shield around the movement, rated to 1,000 gauss | 1956 as the 6541; 116400 from 2007 to 2023 | Milgauss, discontinued |
| Patek Philippe 26-330, 324, 240, 30-255 | Spiromax hairspring in Silinvar silicon, non-magnetic; Pulsomax escapement on some calibres | Spiromax 2006, across the range through the 2010s | Nautilus, Aquanaut, Calatrava, most current references |
| Audemars Piguet 4302, 4401 | Conventional alloy hairspring; the movement meets the standard antimagnetic norm but is not built around magnetism | 2019 | Royal Oak Selfwinding 41 mm, Royal Oak Chronograph |
| Richard Mille | Conventional hairsprings in most calibres; titanium baseplates and bridges are non-magnetic but do not shield the spring | Various | RM 011, RM 035 and others |
A silicon or Parachrom hairspring is the component that matters, because the hairspring is the part that magnetism affects most. A current Rolex or Patek Philippe with one can meet a bag clasp every day and keep its rate; older calibres such as the Rolex 3135, the Patek Philippe calibres before Spiromax and the current Audemars Piguet and Richard Mille movements can still be magnetised by the same clasp. The Patek Philippe Nautilus page and the Audemars Piguet collection pages name the hairspring for each current reference; COSC chronometer testing, which Rolex's calibres pass before Rolex's own cased test, does not include a magnetism test, so a chronometer rating says nothing about it.
The Rolex Milgauss: the watch built for magnetic fields
The Milgauss, from "mille gauss", was launched in 1956 as the reference 6541 for scientists and engineers working near strong fields, particularly at CERN in Geneva, and it resisted 1,000 gauss by enclosing the movement in a soft-iron Faraday cage that diverts magnetic field lines around the calibre. It sold slowly, was discontinued in 1988 and returned in 2007 as the 116400, with a Parachrom hairspring inside the same shielding, an orange lightning-bolt seconds hand and, on the 116400GV, a green-tinted sapphire crystal that Rolex said it would never produce in volume for anyone else. Rolex withdrew the Milgauss from the catalogue in 2023, and no current Rolex carries a Faraday shield; the brand's position is that the Parachrom hairspring and Chronergy escapement make the shield unnecessary for ordinary life. As a discontinued reference with a fixed supply, the 116400 has a following. On 25 September 2026 Bizak's sourced catalogue listed a Milgauss 116400 with white dial at US$10,694 brand new, a pre-owned white dial at US$9,552 and a pre-owned 116400GV with black dial and green crystal at US$9,764, all sourced to order; those figures describe what we saw and will move. Our Rolex price guide explains how to compare quotes for discontinued references.
How to keep a watch away from magnets
- Take the watch off before handling magnetic closures. Or wear the bag on the other arm; the clasp meets the wrist that carries the bag.
- Choose phone and tablet cases without magnets. Or keep the phone in the hand opposite the watch.
- Do not rest the wrist on a laptop. The speakers sit under the palm rest on many models.
- Keep the watch off the fridge door and away from magnetic knife racks and tool holders.
- Remove the watch for an MRI. Every scanner's staff will ask; the field can damage the watch beyond demagnetising.
- Store the watch in its box, not in a drawer with speakers, chargers or magnetic tools.
- Test with a compass once a month. A minute's check catches magnetism before the rate becomes a problem.
When is it magnetism and when is it a service?
Magnetism is the diagnosis when the rate changed suddenly, the watch is otherwise in good order and a compass reacts. A service is the diagnosis when the rate has drifted slowly, the watch is more than about ten years from its last service, the power reserve has shortened over months rather than overnight, or the demagnetiser has been tried and the rate has not recovered. Rolex's guidance is a service roughly every ten years depending on use; Patek Philippe and Audemars Piguet give similar intervals for their automatic calibres, with complicated references serviced more often. A watch that has been demagnetised and still runs badly should go to the brand or an accredited watchmaker with the symptom described in writing, and the invoice should say what was found. A seller who describes a fast-running watch as "just magnetised" without a timing-machine printout has not checked, and the price should assume a service. Our Submariner 126610LN guide and Aquanaut 5167 guide cover the calibres that resist magnetism best in each range.
Quick answers
How do I know if my watch is magnetised?
It suddenly runs fast, often by minutes a day, or stops and restarts when shaken, and it deflects a compass needle when brought close. A slow drift over years is a service issue, not magnetism.
How do you fix a magnetised watch?
A watchmaker passes it over a demagnetiser for a few seconds without opening the case, then checks the rate on a timing machine. It is the cheapest repair in watchmaking and most watchmakers do it while you wait.
Can a phone magnetise a watch?
Yes, through the speaker magnets and, more often, a magnetic folio case or mounting ring. Holding the phone in the hand that wears the watch is the usual route.
Are Rolex watches antimagnetic?
Current Rolex calibres use a Parachrom hairspring and Chronergy escapement that are largely insensitive to magnetism, and some use a silicon Syloxi hairspring. Older calibres such as the 3135 can still be magnetised.
Why was the Rolex Milgauss discontinued?
Rolex withdrew the Milgauss in 2023 and has not said why. Its Parachrom hairspring and Chronergy escapement now give every professional model most of the Milgauss's resistance without a Faraday shield.
Request a Milgauss sourcing quote
Tell us the dial, crystal, preferred year range, condition and whether the warranty card is required, plus your budget and timing, through our sourcing enquiry form. We confirm the specific watch, photographs, card and final price before you commit, and every watch is checked on a timing machine before dispatch. Catalogue entries: Milgauss 116400 white dial, pre-owned Milgauss 116400GV black dial, green crystal, pre-owned Milgauss 116400 white dial; browse the Milgauss collection, the Rolex collection, the pre-owned watches collection, or sell or trade your watch.
Related reading: Submariner 126610LN guide · Explorer 40 224270 guide · Patek Philippe Aquanaut 5167 guide · Rolex price guide.
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