Exact time now
The clock above shows the exact time to the millisecond, corrected against an internet time server. The line under it says how far your own device clock is off.
| Your device clock | measuring… |
|---|---|
| Measurement accuracy | … |
| Network round trip | … |
| Reference | … |
| UTC right now | … |
How the exact time is measured
Your browser asks our server for its clock time several times in a row. Each request takes a little time to travel there and back, so we take the fastest one, assume the reply was sent halfway through the trip, and compare it with your device clock. The difference is the correction. The uncertainty is half the round trip, which on a normal connection is a few hundredths of a second.
The server's own clock is kept on time by the Network Time Protocol, which ties back to the atomic clocks that define UTC.
Why device clocks drift
Computers and phones keep time with a cheap quartz crystal that can gain or lose a second or more a day, depending on temperature and age. They correct themselves by syncing with internet time servers, but not continuously: Windows typically syncs about once a week. If your clock is off, the steps below fix it.
Questions people ask
How accurate is this clock?
The page measures the round trip to our server several times, keeps the fastest sample, and corrects your device clock by the difference. The result is usually accurate to within a few hundredths of a second; the exact margin is shown above.
Is my computer clock right?
The line under the clock tells you. Most computers sync automatically with internet time servers, but some drift by seconds, or minutes if syncing is off or the battery is failing.
How do I fix the time on Windows?
Open Settings, then Time & language, then Date & time. Turn on Set time automatically and press Sync now. Windows normally syncs only about once a week, so a clock can drift a little between syncs.
How do I fix the time on a Mac or iPhone?
On a Mac, open System Settings, General, Date & Time and turn on Set time and date automatically. On an iPhone or iPad, open Settings, General, Date & Time and turn on Set Automatically.
What is the most exact time source?
Official time comes from atomic clocks run by national labs such as NIST in the United States (time.gov) and combined by the BIPM into Coordinated Universal Time (UTC). Our server clock is synced to that chain through the Network Time Protocol.
Other ways to see the time: big digital clock · analog clock · UTC time now · world clock