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.
I purchased on my Android device decided purchased Apple OS version , is very stable and by far best in App Store very well polish and with support sync to atomic clock . I noticed Apple version offer landscape mode compared to Android device and been using for over year now I have collections of over 40 watches and surprisingly I was able to migrate my backup of watches from Android to Apple kudos to Tyler excellent and well polish app
Developer Response
Appreciate the kind words and all of the feedback that has helped me make the app great!
Paid app average
Mygreatreview
I paid for the premium version tested the same watch on the same position same mic nothing changed under high confidence environment and all 10 readings gave me different results. How can that be ??? Some small differences yes but some shows minus and some plus.
Developer Response
Unfortunately, using a device microphone can only be *so* good for measuring the faint ticks of a watch. A lot of the success comes down to environment. Fans humming, dogs walking with their toe nails clicking, a wall clock ticking in the background, your neighbor's radio, etc. If you have patience and desire a truer reference, using the tap measurement option over a couple days will give you a more accurate picture. But otherwise, I do the best I can. If you find there are other apps that do the audio measurements better, please email me and let me know so that I can benchmark. But often, I find competitors present more confidence whereas I err on the side of transparency.
Works
coldsoul77
Great app the free version provided enough usefulness to be worthy of upgrading to the paid version.
Developer Response
I’m glad you thought the app was worth the price! If ever have feedback for how I can improve Chronolog to make the best watch accuracy and timegrapher app, please let me know. Thank you for the review
Pretty good app
Random Haligonian
It’s a pretty good app. Not fancy which makes it easier to use. I both like it and recommend it. TIP: Click on the “info” icon, rather than the “ChronoLog” icon, to see current atomic time. Set your watch to that time then make the first log entry.
Developer Response
I can live with pretty good :) Thanks for taking the time to leave a review. The next version has the atomic time and analog clock face much more prominent!
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:
Purchases
Identifiers
Usage Data
Privacy practices may vary, for example, based on the features you use or your age. Learn More
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
