The watch accuracy and timegrapher app for mechanical watch collectors. Audio check, atomic time sync, and rate tracking — no subscription, no account, one-time purchase.
ChronoLog — Watch Accuracy Tracker & Audio Timegrapher for Mechanical Watches
Track the accuracy of your mechanical watches with professional-grade tools. ChronoLog combines an audio timegrapher, offset measurement logging, and atomic time synchronization into one app — purpose-built for watch collectors and horology enthusiasts who care about precision.
No subscription. No account. One-time purchase unlocks everything.
MEASURE WATCH ACCURACY — THREE WAYS
• Audio Timegrapher: Use your device's microphone to listen to your watch's tick and measure rate (seconds per day), beat error, and amplitude — the same metrics a professional timegrapher provides.
• Photo Offset: Photograph your watch dial against atomic time, enter the displayed time, and ChronoLog calculates the exact offset. The most precise manual method for measuring watch accuracy.
• Tap Timing: Tap when your watch hits a specific second to quickly log an offset. Fast, simple, and works with any watch.
TRACK ACCURACY OVER TIME
Each measurement is logged to a timing run — a series of readings that ChronoLog analyzes together. Monitor your watch's daily rate, see how accuracy changes day to day, and spot regulation issues before they become problems. Tag measurements with conditions like position, temperature, or wear pattern to understand what affects your watch's performance.
ATOMIC TIME SYNCHRONIZATION
ChronoLog syncs with NTP atomic time servers so every measurement is referenced against true time — not your phone's clock. View the live atomic time, compare it to your device, and use it as a precision reference when setting your watches.
DETAILED ANALYTICS & VISUALIZATIONS
Dive into performance graphs that show rate trends, offset history, and accuracy patterns across your entire collection. See at a glance which watches in your collection are your most accurate daily wearers and which need regulation or service.
BUILT FOR WATCH COLLECTORS
• Add unlimited watches with photos, brand, model, serial number, caliber, and notes
• Organize your collection with archive support
• Export all measurement data to CSV for your records or your watchmaker
• Back up and restore your full database across devices
WHY CHRONOLOG?
Whether you're a seasoned collector checking COSC-grade accuracy, a hobbyist curious about your Seiko's daily rate, or a watchmaker tracking regulation results — ChronoLog gives you the tools to measure, log, and understand your watch's timekeeping performance.
Built by a watch enthusiast in Boulder, Colorado.
Download ChronoLog and start measuring your watch accuracy today.
Great app which continues to improve. A must have for any real watch enthusiast. Feature request…Would be good to see specific watch model performance across all uses as a median/mean to understand how our own watches perform against the crowd average.
Developer Response
Thanks for taking the time to check out my app and leave a review! I'd love to hear more about your idea for comparisons. Please reach out to me if you ever want to discuss.
Even logging is paywalled
Mikeer
Can only log 5 measurements for free - even use the most basic functionality is paywalled. May as well just use a spreadsheet.
Developer Response
Hey, I wanted to see how the spreadsheet approach is going? I’ve redesigned the app and added audio tick measurements. Would love for you to take another look! Thanks for the review!
Bug fixes and Stability. Better performance when handling very large collections. Fixing the database restore path. Minor offset-change UI bug fix. Some backend stability fixes.
Version 2.5.1
The developer, tyler wood, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
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Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More