How Accurate Should an Automatic Watch Be?

Your new automatic watch is a few seconds off after a day. Is that a problem? Almost certainly not. Here is what normal looks like, and how to tell when it isn't.

What is normal?

  • Chronometer certified (COSC): −4 to +6 seconds a day on average, tested over 15 days in several positions and temperatures. The benchmark for a high-precision mechanical watch.
  • A well-regulated Swiss movement: within roughly ±10 to 15 seconds a day. Our Elemental is regulated to within ±12 seconds a day.
  • Entry-level Japanese movements: factory tolerances are often quoted at around −20 to +40 seconds a day, though many run far better.

A quartz watch, by comparison, drifts only about 15 seconds a month. Mechanical accuracy is a different game.

Why it varies from day to day

  • Position: dial up, dial down and crown positions all run at slightly different rates.
  • How wound it is: many watches lose a little in the last hours of their power reserve.
  • Temperature and how active you are.

That is why you should judge accuracy over several days, not one.

How to measure it properly

  1. Set the watch to the second against an accurate time source, using the hacking seconds.
  2. Wear it normally for five to seven days, checking at the same time each day.
  3. Divide the total difference by the number of days. That is your average daily rate.

When to worry

Simple ways to improve it

  • Keep it well wound, and wear it daily if you can.
  • Use the night position: if it gains, try crown down; if it loses, try dial up. Many owners balance out a few seconds this way.
  • Keep it away from magnets.
  • Ask a watchmaker to regulate it. A small adjustment can bring it much closer to zero.
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