ClockCheck

Watch accuracy

How true is your watch?

Hold your mechanical watch to your iPhone for 20 seconds. ClockCheck listens to it tick and tells you how many seconds a day it gains or loses.

Coming soon to the App Store

For iPhone. Free to check.

Inside the app

From one tick to a whole watch box.

  • The Check screen: a saffron panel asking “How true is your watch?”, a beat rate picker and a Start check button
    Start a check
  • A result: the watch runs 5.1 seconds slow per day, with high confidence, a tick trace and 28,800 beats per hour
    Your rate, in plain English
  • The Watch Box: a grid of line-drawn watches, each with its average rate and number of checks
    Your whole collection
  • One watch's page: a saffron panel with its average rate over the last 30 days, and the advice “Running within spec”
    How each watch is doing
  • A watch's history: every check plotted against the range its movement is made to run, with the list of checks below
    Every check, against its spec
  • A watch that needs attention: its average rate over the last 30 days and the advice “Time for a service”
    Plain service advice

Screens show sample watches and checks, and follow your device’s light or dark setting.

The 20-second check

A timegrapher in your pocket.

It works like the machine a watchmaker uses, with the microphone already in your phone.

  1. Find a quiet roomPhone face up on a table.
  2. Case back to the microphoneThe holes on the phone’s bottom edge.
  3. Stay still for 20 secondsClockCheck listens to every tick and times it.
Example result
−5.1seconds slow per day

Excellent for a mechanical watch

High confidence. Clear ticks, heard all the way through.

beats per hour
28,800
beat error
0.0 ms
ticks heard
159/160

What you get

Plain numbers, and how far to trust them.

  • Honest about how sure it is

    Every result has a High, Medium or Low confidence rating. If the room was noisy or the watch moved, ClockCheck says so, and rounds the number instead of pretending to be precise.

  • A verdict in plain English

    From “Exceptional accuracy” to “Well off — may need regulating or service”, so you know what the number means. Within two seconds a day earns a crown.

  • Finds the beat rate for you

    It works out whether your movement beats 18,000 or 28,800 times an hour on its own. Know yours? Pick it by hand, from 14,400 to 36,000.

  • A result worth sharing

    Make a picture of your result, with the rate, the verdict and the beat error, and send it anywhere from the share sheet.

ClockCheck is a quick desk check for mechanical watches, not a lab instrument. For a serious regulation job, ask your watchmaker.

Premium

The Watch Box.

The check is free. Premium remembers, so you can see how each watch keeps time over weeks and months.

$1 a month or $10 a year.

US prices. Apple shows your own country’s price. Try it with one watch for free.

  • Your whole collection in one place, with a wish list for the ones you’d like.
  • Save each check to the watch it was for.
  • A simple chart of your readings against what that movement is designed to do.
  • Plain service advice when a watch drifts outside its movement’s range.
  • Your own photo of each watch.

Privacy

The sound stays on your phone.

It’s analysed on your phone and never uploaded. A free check saves nothing. No account, no ads, no tracking, and everything in the Watch Box stays on your phone too. Read the privacy policy.