Why is my watch running fast or slow?

If a mechanical watch that used to keep good time suddenly starts gaining a lot — minutes a day, sometimes minutes an hour — magnetism is the overwhelming favorite. The heart of a mechanical movement is the balance wheel, regulated by a fine coiled hairspring. When that spring picks up a magnetic charge, neighboring coils attract and cling. The spring effectively gets shorter, the balance oscillates faster, and the watch races ahead.

The everyday sources are surprisingly ordinary: the speaker in your phone or laptop, magnetic tablet and laptop covers, magnetic phone mounts and pop-sockets, handbag and bracelet clasps, cabinet catches, and fridge magnets. You don't need an industrial magnet — resting your watch on a laptop speaker overnight can do it.

Losing time points in a different direction than gaining it. A magnetized watch almost always runs fast, so a watch that runs slow — especially if the loss is large or the rate is erratic day to day — more often means the movement is struggling. The usual causes are dried or gummed-up lubricants, accumulated dust, or a mainspring that is simply running down.

The clearest tell is a watch that runs slow and loses power quickly — a symptom of a low balance amplitude, where the movement no longer has the energy to swing fully. Over years, factory oils dry out and thicken, adding friction. This is what a service — a full clean, oil, and adjust — corrects. As a rough guide, mechanical watches are commonly serviced every four to six years, though intervals vary by movement.

Before assuming a service, rule out the simple things: make sure the watch is fully wound, and check it hasn't stopped and restarted (which reads as a loss). If it's slow only when off the wrist overnight, that's a power-reserve issue, covered next — not a service problem.

An automatic watch that keeps good time all day but loses time or stops overnight is usually just running out of power. The rotor only winds the mainspring when your wrist moves. A desk-bound or low-activity day may bank only a handful of hours of reserve, so the watch coasts toward empty overnight, running slow as the mainspring tension falls and finally stopping.

One caveat: if a watch that used to hold a comfortable overnight reserve now dies early even after a full wind, its reserve is shrinking — a sign the movement's efficiency is dropping and a service is due. Want to check the rate itself? Our watch accuracy calculator turns two time checks into a clean seconds-per-day figure.

Quartz movements are extremely stable — typically accurate to within seconds per month — so when a quartz watch runs slow, stops, or behaves oddly, the battery is nearly always the answer. The most recognizable warning is the End-of-Life (EOL) indicator: instead of ticking once per second, the seconds hand pauses and then jumps forward in 2 to 4 second steps.

This is deliberate. Built into many quartz movements, the EOL feature triggers when battery voltage falls below roughly 1.35 volts. By moving the hand in bigger, less frequent jumps, the watch saves power while still keeping accurate time — a clear visual nudge that the battery is nearly done. Replace it and the watch returns to a normal one-second tick.

If a quartz watch is wildly off even with a fresh, correct battery, that's uncommon — it may point to moisture ingress, a damaged coil, or a failing circuit, which is a repair rather than a routine swap. Not sure whether you have quartz or mechanical? Our automatic vs. quartz guide shows how to tell them apart at a glance (hint: watch the seconds hand — a smooth sweep is mechanical, a once-per-second tick is quartz).

Not every deviation is a problem. A mechanical watch is a tiny mechanical governor, not an atomic clock, and a small, consistent daily gain or loss is completely normal. For reference, a COSC-certified chronometer must average between −4 and +6 seconds per day; many good non-certified movements run within roughly ±5 to ±10 seconds per day. If your watch is steadily a few seconds off each day, it's behaving as designed.

Two factors shift the rate without anything being wrong:

• • Resting position. Gravity affects the balance, so a watch runs at slightly different rates dial-up, dial-down, or crown-up. This is exactly why watches are tested and regulated in multiple positions. You can use it to your advantage: if yours gains on the wrist, resting it in a position that loses slightly overnight can cancel some of the daytime gain.
• • Temperature. Heat and cold change the metal and the rate slightly; COSC even tests at 8°C, 23°C, and 38°C. Everyday temperature swings nudge the rate a little.

If a steady error still bothers you, the answer isn't a repair — it's a regulation. A watchmaker adjusts the effective hairspring length to bring the rate closer to zero, usually a quick and inexpensive job. To measure your own rate first, see the accuracy calculator.

The reassuring news: the three most common causes — magnetization, a low battery, and simply not winding an automatic enough — are all cheap and often DIY. Persistent or erratic behavior after those are ruled out is what warrants professional attention.

Why is my mechanical watch suddenly running fast by several minutes a day?

It's almost certainly magnetized. A magnetized hairspring has coils that cling together, shortening the spring so the balance swings faster and the watch gains — sometimes minutes an hour. Everyday phone and laptop speakers, magnetic cases, and clasps are the usual sources. Demagnetizing with a cheap tool or at any watchmaker fixes it in seconds.

How do I know if my watch is magnetized?

The tell is a sudden, large gain where the watch used to keep good time. Confirm it by holding the watch about an inch from a compass and moving it slowly — if the needle follows or swings, it's magnetized. Free smartphone compass or magnetometer apps show the same thing. It causes no lasting damage.

Why is my automatic watch losing time or stopping overnight?

Usually an insufficient power reserve. The rotor only winds when your wrist moves, and a quiet day may store just a few hours of power, so the watch runs slow and stops overnight. Wind it 20–40 turns before bed, wear it more actively, or use a winder. If it dies early even after a full wind, the movement likely needs a service.

My quartz watch's seconds hand jumps every few seconds — what does that mean?

That's the End-of-Life indicator. When the battery drops below about 1.35 volts, the seconds hand pauses and jumps in 2–4 second steps to save power while still keeping accurate time. It means the battery is nearly dead — replace it and normal ticking returns.

How accurate should a mechanical watch be?

A small, consistent gain or loss is normal. COSC chronometers average between −4 and +6 seconds per day; many non-certified movements run within about ±5 to ±10 seconds per day. If steady drift bothers you, a watchmaker can regulate the movement — an adjustment, not a repair.

Does the resting position of my watch affect its accuracy?

Yes. Gravity makes a mechanical watch run at slightly different rates dial-up, dial-down, or crown-up — which is why they're regulated in several positions. If yours gains on the wrist, resting it in a position that loses a little overnight can offset the gain and improve your daily average. Temperature also nudges the rate.

When should I take a fast or slow watch to a watchmaker?

If a mechanical watch stays off after demagnetizing and a full wind, if it runs slow and erratically, if it's been knocked or near a very strong magnet, or if a quartz watch is wrong after a fresh battery. Routine causes — magnetism, low battery, under-winding — you can often fix yourself.