Watch Accuracy Tracker, Explained: How to Actually Measure +/- Seconds Per Day

Every collector eventually asks the same question: is my watch keeping good time? A watch accuracy tracker answers that — but only if you measure correctly.

Two ways to measure

1. Timegrapher (instantaneous rate)

A timegrapher captures rate, beat error, and amplitude in a position. Useful for diagnostics, but a single position rarely matches how the watch performs on the wrist over 24 hours.

2. Real-world rate (deviation over time)

Set the watch to a reference time (atomic clock, phone GPS), wear it normally, then compare again days or weeks later. Divide the deviation in seconds by the elapsed days — that's your real seconds-per-day. This is what Bezelio's accuracy log computes for you.

What good looks like

• COSC chronometer: −4 / +6 sec/day.
• METAS Master Chronometer: 0 / +5 sec/day.
• Rolex Superlative: −2 / +2 sec/day.
• Standard mechanical: ±15 sec/day is normal.
• Quartz: usually within ±15 sec/month.

Patterns to watch for

If your numbers drift out of spec over months, you may be due for a regulation. If amplitude has dropped (per timegrapher), the mainspring may be tired. Logging consistently lets you spot the trend before the watch stops.