How to check your watch's accuracy at home
Measure how many seconds a day your mechanical watch gains or loses with an accurate clock and a few days of wear, and what to do with the result.
Published
What you need
An accurate reference and a few days. A phone clock can be a second or more out. The sync countdown measures how far your device clock is off and corrects for it, so you are comparing against real time.
Steps
Sign in and add the watch to My watches to log each check. It works out the rate for you and keeps a history, so you can see if a watch starts to drift.
- Wear the watch for a day first, or wind it fully, so it is not running on a low mainspring.
- Set it to the exact second with the sync countdown.
- At about the same time each day, open the countdown again and note how many seconds ahead or behind the watch is.
- After three to seven days, divide the total by the number of days. That is your rate in seconds a day.
Why one day is not enough
A mechanical watch runs at a slightly different speed depending on its position, the temperature and how wound it is. A desk day and an active day can differ by several seconds. Averaging over several days gives the number that matters: where the watch will be at the end of the week.
Testing by position
Leave the watch overnight in one position, such as dial up or crown down, and compare the morning reading with the evening one. Try a different position the next night. If one position gains and another loses, choosing where it rests at night can cancel out a few seconds a day.
Timegrapher apps
Apps that listen to the tick through your phone microphone give a rate, beat error and amplitude in under a minute. They need a quiet room and are less reliable than a real timegrapher, but they are a quick check before and after a change.
What the result means
- Within the figures in the accuracy guide: nothing to do.
- Suddenly gaining minutes a day: it is probably magnetised.
- Slowly getting worse over months, or losing power early: it may be due a service.