Rate Log: Watch Accuracy

Watch accuracy log for owners of mechanical and automatic watches. Find out how many seconds a day a watch gains or loses: tap when its second hand reaches 12, and Rate Log works out the rate from your readings.

Taking a reading
- The screen shows the phone clock with milliseconds and one large tap target.
- Rate Log keeps how far the watch is from the phone clock and shows the rate in seconds per day between readings.
- The latest rate comes with a plus-or-minus band that shows how uncertain it is. The band is wide for readings close together and narrow for readings days apart. If the band exceeds the rate, the rate is marked not yet meaningful.
- Time set and Regulated each start a run of their own, so a rate never spans an adjustment to the watch.
- Add a note to a reading, such as slept crown up, and edit or delete readings later.
- A chart shows the offset over time.

Included from the start
- Up to three active watches
- Notes, runs, the offset chart and the rate between readings with its band
- CSV export of your readings, and backup and restore, to a file you choose

Rate Log Lab, one optional purchase
- Unlimited watches
- A trend rate fitted through your readings over 7 days, 14 days, 30 days or the whole run, with its error band and flags for readings that sit far from the line, which you can leave out
- Position tags (dial up, dial down, crown up, crown down, crown left, crown right and worn) and the rate by position
- Before and after regulation sessions, side by side
- A plain-text summary of a watch to hand to your watchmaker
No subscription. Everything under Included from the start keeps working without Lab.

Measured against the phone clock
Every reading compares the watch with your phone's clock. Rate Log does not verify that clock and makes no network time request, so keep Automatic date and time on. The band assumes your tap is off by up to 0.2 seconds either way.

Works offline
Watches, readings and notes stay on your phone. There is no account, and Rate Log does not use the microphone. The only network use is showing the Lab price, buying Lab and restoring a purchase.