The Movement Clinic · Self-test
How to run a rate test on your watch
Applies to any mechanical watch, not only Tudor — this is one of the seven procedures in the section that isn't brand-specific.
Why this test works
A single day of comparison is noise: temperature alone permits about plus-or-minus 0.6 s/d per degree Celsius under COSC, and wrist heat versus a cold nightstand is up to about 9 s/d of legitimate difference. Only a cumulative log over at least a week separates a real rate from measurement error.
What you need
- A reference time source — the protocol uses the free site time.is to sync once at the start and is never reset for the duration of the test.
- A camera for a daily overhead photo or 60fps video showing the dial and the reference time in the same frame.
- Optional: the free tool Toolwatch.io (web and apps, NTP-referenced), or the paid ChronoLog for iOS, whose photo/NTP offset mode is the accurate part.
The steps
- Sync the watch once at time.is, then never reset it for the duration of the test.
- Every 24 hours, shoot a 60fps video or a still photo with both the dial and the reference time display in frame, taken from directly overhead — parallax is the biggest source of bogus readings.
- Log the cumulative offset from the original sync, not a daily reset to zero.
- Run a minimum of 7 days; 14 is better.
- If you can, run two campaigns: worn (real-world rate) and static on a nightstand (the movement's own rate).
What to log
- Date and time of each reading
- Cumulative offset in seconds
- Wind state (fully wound or partial)
- Worn or static, and position if static
- Ambient temperature if known
Reading your result
| Pattern | What it means |
|---|---|
| Mean rate out of spec but stable day to day | Needs regulation only — cheap, and not a health problem. This is the single most over-diagnosed "fault" in watch ownership. |
| Mean rate fine but scatter of about ±10 s/d day to day | The real red flag: dried lubricant, dirt in the escapement, a damaged pivot, or a hairspring intermittently touching. |
Related
Issues this test helps you get to the bottom of:
Use the rate-test logger to track this automatically over 7-14 days, or run the symptom checker for a verdict on your exact watch.
The Movement Clinic is an independent publication by Timekeeper PH. It is not affiliated with, endorsed by, or connected to Tudor or the Rolex Group. This self-test is general guidance, not a substitute for a qualified watchmaker.