Edwin LabWhat is a Unix timestamp?
A Unix timestamp counts elapsed time from the Unix epoch: 1970-01-01T00:00:00.000Z. The number describes one instant in UTC. Seconds and milliseconds are different units for that same count, while a time zone changes only how the instant is displayed.
Seconds, milliseconds, UTC, and WIB
Many APIs and command-line tools use seconds, such as 1704067200. JavaScript's Date.now() returns milliseconds, such as 1704067200000. Both represent 2024-01-01T00:00:00.000Z. In Asia/Jakarta, that instant is 07:00 WIB, or UTC+07:00.
Auto detection is only a digit-count heuristic: values with up to 10 digits are treated as seconds, and longer values as milliseconds. Choose a unit manually whenever the source system specifies one. The selected display time zone does not change the underlying epoch.
Convert an ISO 8601 date
Date to timestamp accepts an ISO date and time with a required zone, for example 2024-01-01T07:00:00+07:00. It converts to 1704067200000 milliseconds and 1704067200 seconds. A fractional part of one to three digits is preserved at millisecond precision.
Dates without an offset, local date formats, impossible calendar dates, and leap seconds are rejected. This avoids guessing which time zone an unqualified date was intended to use.
Frequently asked questions
How can I tell seconds from milliseconds?
Check the API or system that produced the value. Auto detection uses digit count as a convenience, not proof: 10 digits or fewer suggest seconds, while 11 or more suggest milliseconds. Select the known unit manually if it is documented.
What does WIB mean?
WIB is Western Indonesia Time, used in Jakarta and seven hours ahead of UTC. Select Asia/Jakarta to see the date and offset for that zone, including when its rules change.
Why must an ISO date include an offset?
A date such as 2024-01-01T07:00:00 does not identify one instant without a time zone. Add Z for UTC or an offset such as +07:00 so the conversion is unambiguous.
Where does “Use current time” get its value?
It reads the current clock on your device and uses milliseconds. This page does not contact a time server or verify your device clock.
Related developer tools
Preview schedules with the Cron Expression Explainer, inspect token time claims with the JWT Decoder, or browse the Developer Tools directory.