Date and time
Unix Timestamp in Milliseconds: Convert 13-Digit Epoch Time
Many APIs, logs, databases, and JavaScript apps store time as Unix epoch values. The common confusion is whether the number is in seconds or milliseconds.
Use the free Timestamp Converter10 digits usually means seconds
A Unix timestamp like 1716800000 is commonly measured in seconds since January 1, 1970 UTC. It is compact and often used by databases, servers, and command-line tools.
13 digits usually means milliseconds
JavaScript Date.now() returns milliseconds, so the value is usually 13 digits, such as 1716800000000. If a converted date looks far in the future, you may have treated milliseconds as seconds.
Compare local time and UTC
For debugging, check both UTC and local time. UTC is best for server logs and APIs, while local time is easier for human schedules and calendar checks.
FAQ
How do I know if a timestamp is seconds or milliseconds?
As a quick rule, 10-digit epoch values are usually seconds and 13-digit values are usually milliseconds.
Why does JavaScript use milliseconds?
JavaScript Date values are based on milliseconds since the Unix epoch, which gives finer precision than seconds.
Can I convert ISO dates back to timestamps?
Yes. Paste an ISO date into the timestamp converter to see Unix seconds and milliseconds.