ChronoLog • Watch Accuracy
Accuracy and Timegrapher
Free · In-App Purchases
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.
more 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.
2.5.1 6 days ago
What's new in 2.5.0:
• Redesigned Wear Log — browse your wear history in new Calendar, Timeline, and Stats views, with a live banner for the watch on your wrist
• New watch details: record production year and purchase condition
• Quickly scroll through large collections with the new scrollbar
• Optional ticking sound for the Clock
• Refreshed Settings and Manage Data screens
• Safer backups: restores are now validated, and a snapshot is saved automatically first
• A refined new app icon
• Plus various fixes and polish throughout the app
2.5.0 24 Jul
Fixing some bugs and some forms
2.4.1 7 Jul
This update sharpens ChronoLog into an even better timegrapher for your mechanical watches.
• Redesigned audio measurement screen — read your watch accuracy at a glance with a cleaner live view of rate (seconds/day),
beat error, and amplitude.
• New two-line beat trace — watch every tick land in real time as ChronoLog listens to your movement.
• Per-measurement notes — record position, service, or conditions alongside any reading.
• 3D Movement Explorer — orbit a mechanical movement in interactive 3D.
• Smoother camera setup for photo measurements, plus polish throughout.
Measure watch accuracy, regulate with confidence, and keep your mechanical watch collection running on time.
2.4.0 17 Jun
2.3.1 fixes bugs in 2.3.0!
From 2.3.0 Update:
The biggest Chronolog update since launch.
Watchbox redesign
• New card design with hero watch images, inline rate + offset, and a live sparkline trend.
• Toggle comfortable vs. compact density from the tab bar.
• Sort by brand, seconds-per-day, last measured, or last worn — the order updates live as your
data changes.
• Swipe right to wear, left to archive or delete. Restore archived watches from the new Archive
sheet.
Timing & service
• Per-run notes from any run's ••• menu — record position, conditions, or anything worth
remembering.
• Service history: track when each watch was serviced, with add / view / edit from the watch's
edit sheet.
• Refreshed onboarding with clearer guidance on Tap, Photo, and Audio measurements.
Graphs
• Redesigned offset graph — colored lines per timing run with audio overlaid in gold, matching the
rate graph.
Wear tracking
• Edit past wear sessions, add backdated entries, and use the new Least Recent tab to spot watches
overdue for wear.
Premium chrome
• Time Sync, Manage Settings, and Wear Log modals refreshed with consistent title bars, brass
section labels, and matching action pills.
• Streamlined watch summary modal: new title bar, tighter edit form, instant save.
• Cleaner Close affordance on the measurements modal and a tighter onboarding preview that fits
smaller screens.
• Add Watch now captures a purchase currency code.
Cloud sync
• One-way device → cloud backup with batch sync and queue replay (gated by feature flag).
Other
• Richer CSV export now includes run notes, watch notes, and a service history section.
• Purchase currency persists correctly across app launches.
• Spanish language support added.
2.3.1 12 Jun
The biggest Chronolog update since launch.
Watchbox redesign
• New card design with hero watch images, inline rate + offset, and a live sparkline trend.
• Toggle comfortable vs. compact density from the tab bar.
• Sort by brand, seconds-per-day, last measured, or last worn — the order updates live as your
data changes.
• Swipe right to wear, left to archive or delete. Restore archived watches from the new Archive
sheet.
Timing & service
• Per-run notes from any run's ••• menu — record position, conditions, or anything worth
remembering.
• Service history: track when each watch was serviced, with add / view / edit from the watch's
edit sheet.
• Refreshed onboarding with clearer guidance on Tap, Photo, and Audio measurements.
Graphs
• Redesigned offset graph — colored lines per timing run with audio overlaid in gold, matching the
rate graph.
Wear tracking
• Edit past wear sessions, add backdated entries, and use the new Least Recent tab to spot watches
overdue for wear.
Premium chrome
• Time Sync, Manage Settings, and Wear Log modals refreshed with consistent title bars, brass
section labels, and matching action pills.
• Streamlined watch summary modal: new title bar, tighter edit form, instant save.
• Cleaner Close affordance on the measurements modal and a tighter onboarding preview that fits
smaller screens.
• Add Watch now captures a purchase currency code.
Cloud sync
• One-way device → cloud backup with batch sync and queue replay (gated by feature flag).
Other
• Richer CSV export now includes run notes, watch notes, and a service history section.
• Purchase currency persists correctly across app launches.
• Spanish language support added.
2.3.0 9 Jun
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.
2.2.1 2 May
- Adds a Wear Log feature (swipe right on element from collection list)
- Fixes performance issues related to image caching
- More DE localization coverage
- Fixed bug related to sorting by rate
- Added sort by most recently worn
2.1.0 17 Mar
ChronoLog 2.0 — Major Update
NEW: Audio Timegrapher
Use your phone's microphone to measure rate, beat error, and amplitude — just like a professional timegrapher. Hold your watch close, tap Listen, and get results in seconds.
NEW: Atomic Time Sync
Live atomic time display synced via NTP servers. Compare your device clock to true time and use it as a precision reference when setting your watches.
Redesigned Watch Cards
Your collection view has been completely refreshed. See rate and offset at a glance, access Graphs, Measure, and Audio directly from each watch card.
Improved Charts & Filtering
Audio and manual measurements now appear together on rate charts. Filter by tag to compare performance across conditions. Tap any point for details.
Plus: German language support, collapsible timing runs, inline measurement editing, keyboard-safe modals, and dozens of polish improvements throughout.
2.0.0 6 Mar
Adding some code for database version rollback safety.
1.9.10 13 Feb
- Sorting: New “Last measured”, “Brand”, and “Seconds/day” sorts with inline direction toggle; remembers your choice; localized (EN/
DE).
- Atomic time sync: More reliable “true time” via robust HTTP sampling + caching, with diagnostics panels for verification.
- Photo handling: Safer storage using relative paths; option to save photos configurable in Settings.
- Watchbox UX: Sort moved to the app bar; cleaner list with archived section and clearer reorder hint.
- Timing runs: Minor UI polish (e.g., add‑run button layout) and confirmation dialog improvements.
- Performance/stability: General polish across timing, image processing, and app responsiveness.
1.9.9 13 Jan
Lots of new features and bug fixes to make ChronoLog - Watch Accuracy the best watch accuracy measurement tool and timegrapher alternative.
• Atomic time service refresh
• UI much better
• Moon Phase bug fix
• Better Clock screen
These changes help make ChronoLog Watch Accuracy the best watch accuracy meter on iOS.
1.9.7 08/09/2025
Lots of new features and bug fixes to make ChronoLog - Watch Accuracy the best watch accuracy measurement tool and timegrapher alternative.
Fixed a bug that was preventing Premium unlock from being recognized in certain cases.
Fixed a bunch of blocking functions so that the UI is much snappier.
More prominent analog clock face display
More prominent restore purchases button
Transparent messaging where Atomic time sync fails
1.9.6 29/08/2025
Lots of new features and bug fixes to make ChronoLog - Watch Accuracy the best watch accuracy measurement tool and timegrapher alternative.
Fixed a bug that was preventing Premium unlock from being recognized in certain cases.
Fixed a bunch of blocking functions so that the UI is much snappier.
More prominent analog clock face display
More prominent restore purchases button
Transparent messaging where Atomic time sync fails
1.9.5 28/08/2025
- Moon phase function
- UI improvements
- More on device debugging
- Better premium version offering communications
1.9.2 12/08/2025
* Full German translation accessible in the Info page
* Integration with NTP service to provide Atomic Reference Time for precision measurements
* Lot's of bug fixes and improvements
* This was a big release, so if you notice anything strange shoot me an email from the info page!
1.9.1 16/07/2025
* Full German translation accessible in the Info page
* Integration with NTP service to provide Atomic Reference Time for precision measurements
* Lot's of bug fixes and improvements
* This was a big release, so if you notice anything strange shoot me an email from the info page!
1.9.0 08/07/2025
Thanks again for all of the feedback! Minor update with some bug fixes, and UI improvements
- Clock page DST awareness, haptics added
- Fixed UI overflow error preventing adding new Timing Runs with large font sizes
- New "winder" tag added
- Fixed bug preventing navigation when viewing past measurement photo
1.8.5 31/05/2025
Everything I fix or add is from user feedback :)
- Fixed the y-axis scaling in line charts
- Fixed photo persistence issues in the edit measurement form
- Added fast track photo handling
- Database cleanup for image blobs
- Larger measurement buttons
- Added 5-second snap points in time picker
- Fixed various iPad-specific issues
Same as 1.8.3 but this one works
1.8.4 13/04/2025
Everything I fix or add is from user feedback :)
- Fixed the y-axis scaling in line charts
- Fixed photo persistence issues in the edit measurement form
- Added fast track photo handling
- Database cleanup for image blobs
- Larger measurement buttons
- Added 5-second snap points in time picker
- Fixed various iPad-specific issues
1.8.3 11/04/2025
version 1.8 introduces a ton of feature requests
* In settings you can set a preferred measurement method
* Archive watches
* Cleaner graphs
* Better forms
* Bug fixes
* GMT time
Version 1.8.1 is fixing bugs related to Photo Measurements, and the inability to delete the current Timing Run.
1.8.1 02/03/2025
So many feature requests.
* In settings you can set a preferred measurement method
* Archive watches.
* Cleaner graphs
* Better forms
* Bug fixes
* GMT time
1.8.0 28/02/2025
Watch tracker capabilities improved with enhancements to time selector
1.7.0 26/01/2025
ChronoLog is a precision watch tracker at your fingertips!
One day I will test everything and have no bugs to fix
1.6.6 25/01/2025
- Fixing reported bugs
-- measurements around midnight behaving strangely
-- visibility of photo measurements
1.6.5 23/01/2025
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.
more Version 2.5.1 6 days ago
Data Not Linked to You The following data may be collected but it is not linked to your identity:
Purchases Identifiers Usage Data