AtomicClock: Exact NTP Time

Contains adsIn-app purchases
18.6K reviews
Content rating
PEGI 3
500K+
Downloads
Content rating
PEGI 3
Digital Purchases
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About this app

Need the exact time to set a watch, align a wall clock, compare UTC, or catch a moment where seconds matter? AtomicClock shows precise reference time from NTP time servers in a clear analog or digital clock.

NTP servers provide network time referenced to atomic clocks. Choose a predefined or custom time server, then view local time or a UTC clock in 12-hour or 24-hour format. Use AtomicClock as an NTP clock, precision clock, reference clock, or seconds clock for manual time checks.

Practical ways to use AtomicClock

• Set a watch, wall clock, camera, or other device manually
• Compare local time with UTC
• Check precise time before an event or scheduled task
• Keep a clear clock visible while you work using picture-in-picture with Pro

Clock display and signal options

• Analog clock and digital clock views
• Custom time formats, clock faces, hands, and fonts
• Smooth, fluid second-hand movement
• Optional acoustic ticking sounds
• Greenwich Time Signal
• Home screen clock widget with time and date
• Tap actions to hide information, freeze the display, or mute ticking

For technical NTP checks, view details such as the selected time server, round-trip time, and stratum. Accuracy depends on the server, network conditions, and device behavior.

AtomicClock is designed for reference time and manual clock sync. It does not automatically change device system time. The home screen widget uses system time for technical and battery reasons.

AtomicClock is free to use. AtomicClock Pro adds preferred clock styles and fonts, many widget customization options, all tap actions, picture-in-picture, and ad removal. Pro is a one-time purchase through your Google Play account with no subscription.
Precise atomic time — UTC clock, Greenwich Time Signal and clock widget
Updated on
Aug 6, 2026
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Data safety

Safety starts with understanding how developers collect and share your data. Data privacy and security practices may vary based on your use, region, and age. The developer provided this information and may update it over time.
  • This app may share these data types with third parties
    Location, App activity and 2 others
  • This app may collect these data types
    Location, App activity and 2 others
  • Data is encrypted in transit
  • Data can’t be deleted

Ratings and reviews

17.2K reviews
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May 21, 2024
Nice, and useful. I have it set up with the acoustic ticking plus a time signal every minute, which works as a basic exercise timer. I find it runs consistently 0.7s slower than my phone's clock and two wall-mounted radio-controlled clocks. It does, however, precisely match a third, smaller radio-controlled clock. Since the wall clocks are identical I have a 2 vs 2 competition for accuracy. I have no complaint. The author's other apps seem excellent too.
6 people found this review helpful
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Ross Hind
November 16, 2020
Good, simple, but there should be a button to get new info from the time server on demand rather than relying on the scheduled rescnchronisations (which I find are unreliable). Such a button also allows you to figure out how accurate the whole thing is by seeing how much the offset changes between clicks of it. There is such a button in all the other accurate clocks I've used. To avoid confusion, this is nothing to do with syncing the internal clock of the phone. Excellent developer coms!
13 people found this review helpful
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Timo Partl
November 15, 2020
Thanks for the clarification. If you could leave your vote for this request on this item in the feedback forums, that would be great! https://feedback.userreport.com/069bab31-9b4b-478a-b996-32f6161df718#idea/267215
Alan Harris
August 26, 2020
This is a great app which I keep permanently on my phone in order to check the accuracy of my various watches and adjust them from time to time. I also use it to update cooker and microwave clocks when we change from normal to summer time or after power outages. It is absolutely split second accurate compared with my Seiko GPS Solar which takes it's time from satellites. A great feature is that you can change the clock face and background to your taste. No issues at all, highly recommended.
37 people found this review helpful
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What’s new

• Redesigned the color picker for app and widget colors, with presets, a color wheel, and brightness control
• Pro: widget backgrounds can now be customized with color and opacity, and default widget colors follow your Android theme better
• Settings now use clearer icons to make customization options easier to scan
• Custom NTP servers now support host:port entries and better validation before saving