The lowest round-trip latency measured between your browser and the current time-service node. It is typically affected by physical distance, network routing, access quality, and current congestion.
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Device time diagnostic
Clock drift test
Time.ms compares your device clock with calibrated time from sources synchronized with atomic clocks. The results show the clock offset, network delay and estimated error.
This tool requires JavaScript.
Calibrated time minus your device time. A positive value means your device clock is behind; a negative value means it is ahead. This is not network latency, time error, or a UTC or time-zone offset
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Calibrating
Measuring network delay and comparing your device clock with calibrated time.
Syncing • Using device time Note: the value above does not include device-clock drift accumulated after calibration. This is generally no more than ±1 ms per minute, but the actual rate varies by device. The lowest round-trip latency measured between your browser and the current time-service node. It is typically affected by physical distance, network routing, access quality, and current congestion. Network latency describes the measured connection. It is separate from the estimated time-error range and must not be treated as that range or divided in half. This error does not show whether your device clock is fast or slow.
An error range calculated from multiple time measurements, browser timing capabilities, sample consistency, and the network-delay limits established by those measurements.
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Last checked
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What it means
Positive offset means calibrated time is ahead of your device clock. Negative offset means your device clock is ahead.
Live comparison
- Time read directly from your device’s system clock. It does not include the correction calculated by Time.ms during calibration
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- Current time after calibration against a time source synchronized with the global atomic-clock system and compensation for measured network delay
- Open: Home — Calibrated time: - — —
- Calibrated time minus your device time. A positive value means your device clock is behind; a negative value means it is ahead. This is not network latency, time error, or a UTC or time-zone offset
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Diagnostic report
Copy this report when troubleshooting login, certificate, logging, or distributed-system time issues.
Time.ms clock drift report
Up to 100 ms
No action is usually needed. Logging and distributed systems may require tighter limits.
Over 100 ms–1 second
This is unlikely to affect normal browsing. You can leave it as is or check the automatic time settings.
Over 1–60 seconds
Keep the device online and retest after automatic time sync. If available, you can use the system’s Sync now action immediately.
Over 60 seconds or persistent
Sync now and check automatic time settings. This offset can affect sign-ins, certificates, scheduled jobs, and audit trails.
Clock drift FAQ
What is clock drift?
Clock drift is the way a device clock gradually gains or loses time. This test measures the current clock offset; repeating it later can reveal drift.
Will this offset correct itself?
Most computers and phones use a preconfigured automatic time source. An offset after startup, wake, or reconnecting may disappear at the next system sync. Keep the device online and test again later, or use Sync now if the system provides it. Check automatic time settings only if the offset persists.
How does this test estimate accuracy?
Each measurement with the lowest network round-trip delay uses four timestamps to define a possible reference-time range. Time.ms compares several consistent samples, uses their shared range, and includes measured browser and server timing limits. Repeatability determines whether more samples are needed and helps classify result quality.