The favorite app for mechanical watch collectors. Audio timegrapher, 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 just recently got into automatic/mechanical watches, and was looking for a way to measure the accuracy of my timepieces. ChronoLog is straightforward, very easy to use and intuitive. I love that the offset, change and rate are all displayed for you, as well as the graphs that help you visualize the changes. Adding a measurement and/or point is also very straightforward.The ability to personalize each watch with a picture and details of the brand, model, purchase date and purchase price are also nice. When you’ve got multiple watches entered into the app, it really gives you a sense of collection whenever you open ChronoLog.Overall, I think ChronoLog is a solid app for watch enthusiasts.
Developer Response
Can't thank you enough for using my app and for taking the time to share this review. If you ever have any feedback or ideas that would make this app more useful, I'm all ears!
an absolute steal for the functionality
Damon-L
this is my first review on the app store in YEARS. i really can’t remember the last one i did. for the price of entry for this app you get full forever access to catalog your watches with their pertinent data, purchase date, price paid, etc. and with very easily tracking of how slow or fast your watches are running with historical data to see trends over time, as well as the perfect analog clock WITH haptic feedback per second to set your watch right on time very easily. app is attractive and minimalistic to a degree with only the important info displayed. this is the perfect app for someone wanting to casually keep up with watch accuracy.
Developer Response
Thanks for the review! It's a labor of love to build and maintain this side project. Hearing from people who enjoy it is a great reward.
Easy way to measure your automatic watch’s accuracy
Xymantix
I have tried a few apps that aid in tracking your watch’s accuracy, and this one is definitely one of the better ones. First of all, it’s easy to take a measurement - due to its “smart prediction” and big (easy to hit when you’re staring at your watch) button. It also has a clock section that helps when setting the time on a watch, as well as tracking other time zones, GMT, etc. Plus, it has a refined UI and a reasonable price, so it’s been pretty useful!
Larry’s Watches
Lds91
I was a little skeptical when I fist came upon this application! First let me say I have 8 Watches. Ranging from expensive to the more average affordable prices. This app. Not only works extremely well, it is also a lot of FUN!!After mastering the how to’s and the do’s and don’t’s, I find it highly enjoyable. You can track anything with a sweep or second hand!I’ve been surprised how accurate some on my watches are and some not so much. I highly recommend this for anyone owning a watch.
Developer Response
Glad you took the time to get acquainted to the app and found it useful! Don’t hesitate to reach out if you have feedback on how it can be improved!
NEW: Spanish language support
The full app — watch accuracy logs, timegrapher, charts — now available in Spanish. Select Español under Settings → Language.
NEW: Movement Type & Battery Tracking
Tag every watch as Automatic, Manual Wind, Quartz, or Solar. Quartz watches now track battery type and last-changed date alongside the rest of your collection details.
Smarter Wear Log Stats
A new "Most Recent" tab shows when each mechanical watch last left your wrist. "Most Worn" and "Most Frequent" now list every watch in your collection — not just the top five.
Music No Longer Interrupted
Opening the watch app no longer pauses your music or podcasts. The microphone is only claimed when you start an audio timegrapher session.
Better Audio Timegrapher Over Time
Timegrapher sessions now send anonymous diagnostic data (no audio recorded) so beat detection, rate, and amplitude keep getting more accurate across a wider range of mechanical watches.
Performance & Polish
Faster timegrapher beat-lock, smoother live rate updates, and fixed text-input freezes. Action buttons restored for previously archived watches.
Version 2.2.1
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
