Reference time when seconds matter

Exact NTP time: check precise current time from selected public or custom time servers.
Local time and UTC: switch between your local clock and UTC for technical work, travel, radio, astronomy or photography.
Analog and digital display: use a readable clock with smooth second hand, ticking sound and customizable time formats.
For real-world clocks: set watches, wall clocks, cameras and other devices manually against a trusted reference.

Choose your time source

AtomicClock can use predefined NTP servers or your own server. It shows practical timing details such as round-trip time and stratum, so you can understand the quality of the current time reference without turning the app into a network tool.

Time serversNTPSelect a public server or add your own.

Connection detailsRTTView round-trip time for the current request.

Server qualityStratumSee the stratum reported by the selected server.

Clock widgets on Android and Windows

Keep time and date visible at a glance. AtomicClock includes customizable clock widgets on Android and Windows, while the main app remains the place to check precise NTP reference time and advanced clock settings.

Built for each platform

AtomicClock is available on Windows, Android, iPhone and iPad. The core idea is the same everywhere, while a few features follow what each platform allows.

Windows: desktop clock display, Windows widgets and optional Windows system time synchronization with AtomicClock Pro.
Android: precise clock display, customizable home screen widget and screen tap actions for quick control.
iPhone and iPad: precise clock display with local time, UTC, clock customization and screen tap actions.

Unlock AtomicClock Pro

AtomicClock is free to use. AtomicClock Pro adds more customization and removes ads, with a one-time purchase on the platform where you buy it.

More clock styles: choose preferred clock faces, hands and fonts.
No ads: keep the clock display focused.
Windows time sync: synchronize the Windows system clock with accurate NTP time.
Android customization: unlock more widget options and screen tap actions.

Feature overview

Show precise current time from NTP servers
Select predefined time servers or add a custom server
Switch between local time and UTC
Use 12-hour or 24-hour time formats
Customize the displayed time format
Display analog and digital clock views
Choose different clock faces, hands and fonts with AtomicClock Pro
Show a smooth second hand and acoustic ticking
Use the Greenwich Time Signal
Show technical NTP details such as round-trip time and stratum
Use clock widgets on Android and Windows
Synchronize Windows system time with AtomicClock Pro

Frequently asked questions

Is AtomicClock a physical atomic clock?

No. AtomicClock is an app that displays time from NTP servers. Those servers typically use time sources connected to real atomic clocks, so the app gives you a practical reference clock without claiming laboratory-grade accuracy.

How accurate is AtomicClock?

Accuracy depends on the selected NTP server, network conditions and device behavior. AtomicClock shows useful details such as round-trip time and stratum to help you judge the current connection.

Can AtomicClock change my device time automatically?

The main app displays reference time for comparison. On Windows, AtomicClock Pro can also synchronize the Windows system clock. Android, iPhone and iPad use the displayed time as a reference instead of changing the system clock automatically.

Do widgets use NTP time?

Widgets are designed for quick time and date display. On Android, widgets use Android system time for technical and battery reasons. Open AtomicClock itself when you want to check precise NTP reference time.

What does AtomicClock Pro include?

AtomicClock Pro unlocks more clock faces, clock hands and fonts, removes ads and includes upcoming Pro features. On Windows, Pro also enables Windows system time synchronization. On Android, Pro adds more widget customization and screen tap options.