Free online timegrapher
Measure your watch's accuracy in the browser.
Hold your mechanical watch right up to your microphone in a quiet room and press start. You'll see the daily rate, beat rate, and beat error build live — the same way a bench timegrapher works.
— s/day
—bph
—ms beat error
—ticks
—elapsed
Microphone access is requested when you press start. Audio is analysed locally in your browser and never uploaded.
This is the quick check. The app is the instrument.
Isochron for iPhone uses raw, unprocessed audio for reference-grade readings — plus amplitude, positional tests, history, and the community.
Get Isochron
Isochron for iPhone uses raw, unprocessed audio for reference-grade readings — plus amplitude, positional tests, history, and the community.
How the online timegrapher works
A mechanical watch ticks 5–10 times per second. Each tick is a tiny click from the escapement, and the spacing between clicks tells you whether the watch runs fast or slow. This page band-passes your microphone signal around the click frequencies, detects each tick, and fits a line through their timing to compute the rate in seconds per day. The alternating tick–tock asymmetry gives the beat error.
Tips for a clean reading: use a quiet room, rest the watch case directly against the microphone (on laptops it's usually near the keyboard or camera), keep everything still, and give it 20–30 seconds to settle. If the rate won't lock, try selecting your watch's beat rate instead of auto-detect.
What's a good result? Chronometer-certified movements run −4 to +6 s/day. Most healthy mechanical watches sit within ±15 s/day. Browser microphones apply some processing we can't fully disable, so treat this as an estimate — the Isochron app records raw audio for reference-grade numbers.