Check our accuracy yourself

Any server time tool can show milliseconds. Here you can check whether those digits are right, ours included, against a clock whose error you know in advance.

A server whose clock we set off on purpose

check.onthesecond.com is a server whose clock we set off standard time on purpose. The amount changes every day at 00:00 UTC, and today’s answer is below.

You can also enter the same address in any other server time tool. If it shows a different number, it is off by the difference. A tool that reads only whole seconds can be off by up to 1 second.

Our results, every 10 minutes

8 min ago, the answer was +0.845s and we measured +0.847s ±3ms, 2 ms apart. Last 7 days: 1008 measurements. Largest gap: 3 ms.

Self-check against standard time

Every 10 minutes our server also measures an internal server whose clock is exactly on standard time, with the same code. The answer there is 0. If our reading drifts from 0, our standard time reference or our measuring code is wrong, and our health check reports a failure. Last 7 days: 1008 measurements. Largest gap: 1 ms.

Our server clock

chrony keeps our server clock on standard time. Its own estimate of the largest possible error was 0.42 ms 8 min ago, and at most 0.64 ms over the last 7 days.

This is chrony’s own estimate, assuming its reference servers are right, not a direct measurement against UTC. The self-check above uses the same server clock, so it can’t catch an error here.

What this shows, and what it doesn’t

This checks our measuring method and our standard time. It can’t check the clock inside a ticket site’s back-end systems, which nobody outside can see. More in how it works.