Timegrapher

How to check your mechanical watch's accuracy with an iPhone

A timing machine tells you how fast or slow a mechanical watch runs and how healthy its movement is. Timegrapher turns your iPhone into one, using the microphone. A quiet room and firm contact give the steadiest reading.

At a glance

Rate
Seconds gained or lost per day
Amplitude
How far the balance swings
Beat error
Tick against tock, in ms

  1. Install Timegrapher

    Download Timegrapher from the App Store. Your first watch is free. Allow microphone access when it asks.

  2. Wind the watch

    Give a hand-wound watch a full wind, or wear an automatic for a while first. Amplitude is lower on a watch that is nearly run down.

  3. Add the watch

    Tap Add watch and enter the brand, reference and movement. Set the Lift angle for your calibre, because the amplitude depends on it. Identify from Photo can suggest the brand and model.

  4. Find a quiet spot

    A fridge hum or traffic costs accuracy. Take off Bluetooth headphones so the iPhone's own microphone listens.

  5. Measure

    Tap Measure and rest the bottom edge of the iPhone firmly on the watch, ideally on the glass. Direct contact carries the ticks far better than air. The measurement stops by itself at 0:30.

  6. Read the result

    You get the rate in seconds per day, the amplitude in degrees, the beat error in milliseconds and the beat rate, with a verdict from Excellent to Service needed and the reasons for it. The Guide tab explains each number.

  7. Try other positions

    Rates change with position. Measure in positions takes the watch dial up, dial down and on its edge, and shows the spread between them.

  8. Check for magnetism

    If the watch suddenly gains a lot of time, tap Check magnetism. It uses the iPhone's magnetometer and tells you whether the watch needs demagnetizing.

Good to know

Watch it over time

Every reading is saved and charted, so a movement that slowly drifts shows up before it stops.

A day on the wrist

Rate from photos compares two dial photos taken a day apart and shows how the watch ran while you wore it.

What it's worth

The price check gets current Chrono24 asking prices for your exact reference and keeps the median.

Pay once

The first watch is free. Timegrapher Pro adds unlimited watches for one payment, with no subscription.

Written for Timegrapher 2.8, October 2026.