Buyer beware! Why your iPhone could harm your precious watch

Borna Bošnjak

You’ve just replied to an Instagram message praising how beautiful your new watch is, after snapping a wrist shot tagged #NWA. Slipping your phone back into your pocket, you rest your arms on your lap, continuing to trundle along on the train ride home. While the wrist shot took a bit of thought and planning, you’d never consider for a moment how you interact with your phone. But that disregard might just make you late for the next train. I’m talking about magnetism, of course, and its eagerness to mess with the delicate hairsprings of mechanical watches.

Why you should care

Until recently, magnets were relegated to phone speakers and were much easier to avoid. Despite their small size, they could still have lasting effects on timekeeping, as explored here by Jordan Ficlkin of Professional Watches, testing an iPhone 12. However, with new generations of iPhone including MagSafe capabilities, the number of magnets and strength of magnetic fields increased. Surprisingly, the magnet array and other areas of the phone had no effect on the watch being tested, apart from the alignment magnet. Used to hold MagSafe accessories in the correct orientation, placing a watch within approximately half a centimetre of it caused dramatic changes in timing. Making it a bit more scientific, @watchoosy tested the iPhone 12 and its accessories, finding that the phone itself produces 57 Gauss and the MagSafe charger 123 Gauss. In this Instagram post, Harry Tan of @watchinghorology showcases the strength of the field on an iPhone 13 Pro, which some reviewers believe have even stronger magnets that its predecessor.

What you can do about it

Thankfully, there are three possible solutions, all with their own benefits and compromises. The first is easy – get a different phone! While magnets are going to be present in any phone with a speaker (not having a speaker would defeat the phone’s purpose, I feel), MagSafe is still a relatively recent addition to the iPhone. Older iPhones are famous for being well-supported by Apple’s software updates, but if it needs to be shiny and new, there are plenty of fish in the Android sea.

If you’re dead-set on an iPhone, there are also plenty of watches out there that boast magnetic resistances well above the highest Gauss number produced by an iPhone or its accessories. Highly resistant watches like the Rolex Milgauss or any METAS-certified Omega will handle those fields with ease, but what if you’re after something more affordable? Interestingly, ISO-certified dive watches require a resistance of 4800 A/m, which equates to about 60 Gauss. While it can’t match the big boys, it could be all you need to protect against an iPhone at a much lower price.

To reduce the magnetism emanating from the back of your phone outright, some report a clear drop in attraction of their MagSafe accessories when using a case that doesn’t support MagSafe.

Thankfully, a magnetised movement is not the end of the road for any watch. A short trip to your watchmaker or a browse for the cheapest demagnetiser on eBay should resolve the issue without too much trouble. After all, every magnet also has its positive side.