iPhone · iOS
Turn your iPhone into a mechanical watch timegrapher.
Measure how accurately your mechanical watch runs using your iPhone’s built-in microphone. See live rate, beat error and amplitude readings. No additional equipment required.
No cables. No special equipment. Just your iPhone and a mechanical watch.
See TG Timer in Action
Watch TG Timer analyse a real mechanical watch using an iPhone. The readings shown are real application measurements, not simulated. · Watch on YouTube
Everything You Need to Understand Your Watch’s Performance
Measure Your Watch
See how many seconds per day your mechanical watch gains or loses.
Understand the Movement
Measure beat error and amplitude alongside rate for a deeper view of movement performance.
Track and Share Results
Review live measurement history and generate PDF reports for your records.
Three Steps to Your First Measurement
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Position Your iPhone
Stand the iPhone upright with its bottom edge resting gently on the watch crystal, in a quiet spot. The signal bar confirms it’s hearing the tick.
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Select Your Movement
Choose from over 3,700 movement presets, or leave BPH on Auto-detect. The preset sets the correct lift angle for accurate amplitude.
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Start Measuring
Tap Play and watch the live readings develop and settle. A signal trace shows them converging, then firming up to ‘stable’.
Start With the iPhone You Already Own
TG Timer uses your iPhone’s built-in microphone to listen to the ticking of a mechanical watch — no cable, hub or accessory required. Rest the phone on the watch and measure.
For workshop environments or challenging measurements, an optional piezo contact microphone is also supported via a USB-C audio adapter — TG Timer detects it automatically. It’s an enhancement, not a requirement.
Built for Watch Enthusiasts and Watchmakers
Rate, beat error & amplitude
Rate shows how many seconds per day the movement gains or loses. Beat error measures how evenly the escapement divides each second between its two half-beats, in milliseconds. Amplitude shows the angular swing of the balance wheel in degrees — a reliable indicator of mainspring condition and lubrication.
Live signal trace & stable readings
A reading builds on screen within a few seconds and keeps refining live as it listens. A live signal trace shows the individual readings settling onto the answer, and it firms up to ‘stable’ once they agree. It never times out — leave it running as long as you like to be certain the reading is rock-steady.
BPH detection, lift angle & 3,700+ presets
Pick your movement from over 3,700 presets and the correct BPH and lift angle are set automatically, giving accurate amplitude without manual configuration. BPH can also be left on Auto-detect when the movement is unknown.
Calibration
A Calibration field on the Setup tab lets you compensate for any systematic offset against a known-rate reference movement.
PDF reports
Tap the share icon to open the report form. Enter the watchmaker name, customer name, brand, movement, serial number and position, then generate a PDF including all readings, the rate-history chart and the analysis count. Share it from the iOS share sheet.
Optional contact microphone
For the strongest signal — especially in a noisy workshop — add a piezo contact microphone via a USB-C audio adapter. TG Timer detects it automatically. Typically under £30, and entirely optional.
Precision Measurements, Explained
On most movements, TG Timer’s rate readings agree with a calibrated bench timegrapher to within 1–2 s/d, beat error to around ±0.1 ms, and amplitude — with the correct movement preset and lift angle — to within roughly ±5°. A Calibration field lets you compensate for any systematic offset against a known-rate reference.
Acoustic measurement depends on a good signal: a quiet room and firm contact between phone and watch. Results vary with movement, condition and environment, and an iPhone will not match a professional bench instrument under all conditions. A side-by-side comparison against a calibrated bench timegrapher is planned.
Your Watch. Your iPhone. Your Data.
Audio analysis and all measurements are processed locally on the iPhone. No account, no Wi-Fi and no server are involved, and nothing is transmitted anywhere. The app has no analytics or telemetry; microphone access is used only while a measurement is running. See the privacy policy for full detail.