Why Your Watch Runs Fast (and What Accuracy Is Normal)

Your phone is accurate because it asks a network of atomic clocks what time it is. Your mechanical watch is accurate because a wheel the size of a lentil swings back and forth eight times a second, in a metal case, on a moving wrist, at whatever temperature the day happens to be. Judged against the phone, every mechanical watch is broken. Judged against what it is, a few seconds a day is a small miracle — and knowing which few seconds are normal tells you whether you need a five-minute adjustment or a five-hundred-pound service.

Measure your rate properly

Set the watch against an accurate reference, leave it a few days, then enter how far it has drifted. Days matter: one night tells you almost nothing, a week tells you the truth.

Bands reflect general expectations for a mechanical watch in good order. Certified chronometers are tested to tighter limits — Omega describes the ISO 3159 chronometer standard as −4/+6 seconds a day, or −5/+8 for smaller calibres, and Rolex advertises −2/+2 for its own certification after casing. Quartz plays a different game entirely: ordinary quartz drifts around fifteen seconds a month, and thermocompensated quartz a few seconds a year.

How to do the measurement properly

1. Set it against an atomic reference, not another watch. Hack the seconds hand to the exact minute.
2. Wear it as you normally do. A rate measured on a desk is not the rate you will experience.
3. Rest it in the same position every night — dial up, for example — because position changes the rate on its own.
4. Check at the same time of day, and record the deviation rather than resetting it.
5. Average over five to seven days. A single day can be off by several seconds for reasons that mean nothing.

Why it drifts: the five real causes

Tap the symptom that matches yours.

The trick nobody tells you

A mechanical watch does not have one rate — it has several, depending on how gravity pulls on the balance. The same watch might gain eight seconds a day lying dial-up and lose three sitting crown-down. Since it spends every night in whatever position you leave it, you can cancel out part of your daytime error for free: if your watch runs fast, rest it overnight in the position where it runs slowest, and vice versa. Try dial-up, dial-down and crown-down for a few nights each and keep the one that lands closest to zero.

Rate is what you notice; amplitude is what matters. A watch keeping perfect time on weak, tired oil is a watch about to become an expensive repair.

Regulate, demagnetise, or service?

One warning about servicing that costs collectors real money: ask explicitly for no polishing. A well-meaning polish rounds the case edges and erases the crisp lines that make a vintage watch valuable — the only condition damage on this page that is genuinely irreversible. See also what actually drives a watch’s value.

What a timing machine tells your watchmaker

• Rate — seconds per day, measured in several positions rather than one. This is the number you feel.
• Amplitude — how far the balance swings. The real health indicator: low amplitude means dirt, dry oil, or a tired mainspring, and it shows up long before the watch starts obviously misbehaving.
• Beat error — whether the swings are symmetrical. A high beat error makes a watch fussy about starting and unstable in different positions.

That is why “it keeps good time” is not the same as “it doesn’t need a service”. A movement can compensate its way to a decent rate while its lubricants turn to varnish and its pivots wear.

Normal mechanical

Roughly −10 to +20 seconds a day, worn

Well regulated

Within about ±5 seconds a day

Certified chronometer

−4/+6 a day, tested before casing

Ordinary quartz

About ±15 seconds a month

Sudden change

Suspect magnetism first, always

Service interval

Every 5–7 years, and never with polishing

The takeaway

Measure over a week, not a night. Compare the number against what your movement was actually built to do, not against your phone. If the rate is consistent, it’s a regulation job or a free trick with overnight positions; if it changed suddenly, demagnetise before you panic; and if it wanders day to day or the watch stops early, that’s the movement asking for a service. A mechanical watch that runs a few seconds off is working exactly as designed — the drift is the sound of it being a machine rather than a signal.