Timestamp Converter
Convert Unix timestamps to ISO, UTC, and local time, and convert dates back to timestamps.
Timestamps are converted locally with your browser time zone data. Nothing is uploaded.
Timestamp converter
Convert a Unix timestamp to a readable date, or turn a date and time into seconds and milliseconds. Nothing is sent to a server.
A 10-digit number is read as seconds, a 13-digit number as milliseconds. A date without a time zone is interpreted in the time zone selected above.
How the conversion works
A Unix timestamp counts the seconds since 1 January 1970 at 00:00 UTC, ignoring leap seconds. JavaScript stores dates in milliseconds, so seconds are multiplied by 1000 before formatting. The ISO 8601 column always uses UTC with a Z suffix, which is the unambiguous form to store or exchange.
Seconds, milliseconds, or text
Input made only of digits is treated as an epoch value. Up to 11 digits is read as seconds and 12 or more digits as milliseconds, so both 1700000000 and 1700000000000 give the same instant. Anything else is parsed as a date string such as 2024-05-01T10:30, 2024-05-01 10:30:15, or 2024-05-01T03:30:00Z. Text with an explicit Z or offset is absolute.
Which time zone is used
UTC is fixed. Local follows your device. The named zones are resolved with the browser Intl API, so Jakarta, Makassar, and Jayapura stay at +7, +8, and +9 while London and New York follow their daylight saving rules. A date typed without an offset is read as wall-clock time in the selected zone.
Frequently asked questions
Is the timestamp in seconds or milliseconds?
Count the digits. Ten digits is seconds and covers the years 2001 to 2286. Thirteen digits is milliseconds. A ten-digit value read as milliseconds lands in January 1970, and a thirteen-digit value read as seconds lands far in the future, which is the usual sign that the wrong unit was assumed.
Why does the same timestamp show a different hour?
An instant is the same everywhere, but the wall clock reading depends on the zone. Daylight saving shifts in London and New York change the offset by an hour, while Jakarta has no daylight saving at all.
Are leap seconds handled?
No. Unix time and JavaScript dates both ignore leap seconds, so a timestamp that falls exactly on a leap second is not represented. For everyday logging, scheduling, and API work this makes no practical difference.