Check whether a device clock is noticeably wrong
Troubleshoot mismatched login codes, logs or meeting times.
Time & Date Tools
Exact Network Time
Calibrate the displayed clock from repeated low-latency server samples and compare it with your device clock. The result is a network estimate, not a claim of atomic-clock precision.
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What this tool does
Show calibrated time, device time and their offset together.
Display round-trip latency, estimated uncertainty, IANA zone and UTC offset.
How to use it
- 1Stay online, start a resync and wait for the sample set to finish.
- 2Read the fast/slow offset together with latency and uncertainty.
- 3Choose 12/24-hour format and optionally show milliseconds.
- 4The page resyncs after regaining focus; use fullscreen for a desk clock.
Practical uses
Explain network time measurement
Demonstrate clock offset and latency together in a classroom or technical session.
Compatibility, privacy and limits
Processed in your browserHTTPSMobile + Desktop
Requires network access to /api/time. If the Worker is unavailable, HTTP Date is only a lower-precision fallback; browser scheduling and network jitter affect the estimate.
Frequently asked questions
Is this atomic-clock time?
No. It estimates current time from server timestamps and round-trip latency, and shows an uncertainty range.
Why does the offset vary between runs?
Routing, device load and browser scheduling change. Repeated samples and low-latency selection reduce their effect.
Can the page fix my system clock?
No. A web page cannot change the operating-system clock; it only reports the difference and general setup guidance.
Does it work offline?
The page can open offline, but it cannot obtain a new network sample and will show device time with an offline notice.