Watch Timegrapher App – Check Mechanical Watch Accuracy

The Rehaut 1775 Watch Timegrapher uses your phone microphone to listen to the tick of a mechanical watch and estimate its timing performance — including rate per day, beat error, amplitude, and measured BPH. No extra hardware required.

What the Timegrapher measures

• Measured BPH — The actual beats-per-hour detected from the audio, useful for confirming your movement or identifying a regulation issue.
• Rate per day — How many seconds per day the watch is estimated to gain or lose relative to a perfect time source.
• Beat error — The difference in milliseconds between the tick interval and the tock interval, a measure of lever symmetry.
• Amplitude — An audio-derived estimate of how far the balance wheel swings with each beat, in degrees.

Supported beat rates (BPH presets)

• 18,000 BPH — Vintage and early movements
• 21,600 BPH — Seiko SKX, some vintage Swiss
• 25,200 BPH — Modern Omega, some JLC movements
• 28,800 BPH — Swiss Standard, most modern Swiss watches
• 36,000 BPH — Hi-Beat: Rolex, Grand Seiko, JLC
• 57,600 BPH — Ultra Hi-Beat movements
• Custom BPH — Enter a custom beat rate for other movements

How to use the Watch Timegrapher

1. Move to a quiet room with minimal background noise.
2. Place the watch caseback flat against your phone microphone.
3. Select the beat rate that matches your watch movement.
4. Tap Start and keep both the watch and phone completely still.
5. Wait for the reading to stabilise, then note the results.

Understanding your readings

What does rate per day mean?

Rate per day shows how far ahead or behind the watch runs over 24 hours. COSC-certified movements fall within +6 / −4 s/d. Most service-ready movements sit within +/−15 s/d.

What is beat error?

Beat error describes how evenly spaced the tick and tock are. Values below 0.5 ms are excellent; above 1.0 ms may indicate a misaligned lever or a movement needing service.

What does amplitude mean?

Amplitude estimates how far the balance wheel swings each beat. A well-serviced movement typically shows 270°–315° when fully wound. Low amplitude below 220° can indicate worn jewels, dry oil, or a weakened mainspring.

Why does selecting the correct BPH matter?

Choosing the wrong BPH causes the rate calculation to use an incorrect interval, producing a wildly fast or slow reading even if the watch runs well.

Why may vintage watches give different readings?

Decades of use, dried oil, and worn pivots cause vintage movements to run with less consistency. Use the Timegrapher as a guide rather than a definitive measurement for recently unserviced vintage pieces.

Common causes of a weak or unstable signal

Ambient noise, a loose grip, tapping the table, or background music all introduce interference. Very quiet movements such as quartz or heavily damped rotors may not produce a strong enough signal.

When should you see a professional watchmaker?

Consider a service if the rate is consistently more than 30 s/d off, amplitude reads below 220°, beat error is above 1.5 ms, or the movement sounds irregular. Always consult a qualified watchmaker for service decisions.

Privacy

Microphone access is used solely to capture the tick sound of your watch during a live analysis session. Rehaut 1775 does not record, store, or transmit audio from your microphone. The Timegrapher does not display private recordings, vault information, watch serial numbers, receipts, journal entries, or personal account information.

Disclaimer

The Rehaut 1775 Watch Timegrapher provides informational estimates derived from audio analysis. It is not a calibrated instrument and does not replace professional watchmaker testing, servicing, diagnosis, or authentication.

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