Free tool · nothing leaves your device
Watch Accuracy Tracker
Log how many seconds your watch is off every day or two. This tracker charts the drift and works out your watch's real seconds-per-day rate over time, far more reliable than a single reading, and it tells you how you stack up against chronometer standards.
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How far off is your watch right now?
Compare your watch's second hand to the exact time, then enter the difference. Log a new reading every day or two. The rate sharpens with each one.
How the tracker works
Your watch's accuracy is measured in seconds per day: how much time it gains or loses in 24 hours. The catch is that a single measurement is unreliable. A watch that sat crown-up overnight can read very differently from one that lay dial-down, and one reading can't tell a genuine rate from a fluke. So instead of one snapshot, this tool records several readings over days and fits a straight line through them.
What counts as a good rate?
A mechanical watch is a tiny machine, not an atomic clock. "Normal" is a wide range, and being a few seconds off a day is nothing to worry about. Here is how the numbers break down.
| Rate (per day) | What it means |
|---|---|
| ±0 to 2s | Chronometer-grade. Rolex's Superlative standard is −2/+2. Exceptional for a mechanical watch. |
| −4 to +6s | The official COSC chronometer range. Very good. |
| up to ±10s | Good for a standard automatic or mechanical watch. |
| ±10 to 20s | Normal and healthy for an uncertified movement. Not a fault. |
| ±20s+ | Running rough. Often magnetism (a 10-second fix) or a service coming due. |
| Quartz: ±0.1–0.5s | Quartz is roughly 100× steadier. More than ~1s/day may mean a weak battery or ageing crystal. |
Why is my watch running fast or slow?
If your rate suddenly jumps, work down this list before assuming the worst:
- 1.Magnetism. The number-one cause of a watch suddenly gaining a lot. Phones, laptops, speakers and magnetic clasps can magnetize the hairspring. A watchmaker demagnetizes it in seconds, often for free.
- 2.Position. A mechanical watch runs at slightly different rates dial-up, crown-down, and so on. If it gains on the wrist, try resting it in a different position overnight.
- 3.Power reserve. Rate can drift as the mainspring winds down. Keep an automatic well worn, or fully wind a hand-wound piece before measuring.
- 4.Service due. Old, dried-out lubricant makes a movement run erratically. Most mechanical watches want a service every 4–7 years.
Frequently asked questions
How many seconds per day is normal for a watch?+
A good mechanical watch runs within about 10 seconds per day. A COSC chronometer must run −4 to +6, and Rolex's Superlative standard is −2 to +2. A normal uncertified watch running 15–20 seconds off is not broken. Quartz is far tighter, usually a fraction of a second per day.
Why is a tracker better than a single reading?+
One reading mixes up how you set the watch with how it actually runs, and can be thrown off by the position it sat in. Logging several readings over days lets the tracker fit a line through your data and read the true average rate, which is much more reliable.
Why does my watch run fast or slow?+
The most common cause of sudden fast running is magnetism, fixed in seconds with a demagnetizer. Other factors are resting position, power reserve, temperature, and being due for a service. Rates far outside normal usually mean a service is needed.
Is my data private?+
Yes. Everything is stored only in your browser using local storage. Nothing is uploaded, so your readings stay private and the tool works offline.
Can I track more than one watch?+
Yes. Add and name multiple watches and switch between them with the tabs above. Each keeps its own history and rate.
How long should I track for?+
You get a usable rate after two readings a day or two apart, but a week of readings is much more trustworthy, especially for automatics, whose rate varies with how active you are.