The epoch is UTC midnight
Zero is 1970-01-01 00:00:00 UTC. The same instant is 1970-01-01 09:00:00 in Korea Standard Time.
Unix time converter
UTC & Unix
Timestamp Converter
Turn a number into a date or a date into Unix time. The converter distinguishes seconds, milliseconds, microseconds and nanoseconds, then shows UTC, Korea time, your device time and an exact ISO 8601 value.
Choose the tool for your task
Each page focuses on one job. Use batch conversion for long logs and the dedicated UTC–KST page when comparing those two time standards.
Number to date
Timestamp → date
Convert seconds, milliseconds, microseconds or nanoseconds into UTC, KST and ISO dates.
Open converter → Date to numberDate → Unix time
Interpret a calendar date in the selected time zone and calculate Unix units.
Open date converter → Live valueCurrent Unix time
See current seconds, milliseconds, UTC and Korea time side by side.
View current time → Nine-hour offsetUTC ↔ KST
Convert UTC and Korea Standard Time while correctly handling date changes.
Convert time zones → Format validatorISO 8601 validator
Validate a date string with Z or a numeric UTC offset and normalize its instant.
Validate a date → Many valuesBatch timestamp converter
Convert multiple values into a table and compare their UTC and KST dates.
Convert a batch →How to read Unix time correctly
The number itself contains no time zone. Treat the unit and the display time zone as two separate choices to avoid most conversion errors.
The unit changes the date
Read as seconds, 1704067200 is 2024-01-01. Read as milliseconds, the same digits point to a date in January 1970.
KST is UTC+09:00
Korea stays nine hours ahead of UTC throughout the year. A late UTC time may already be the following calendar day in Korea.
| Example input | Typical unit | UTC result | Use |
|---|---|---|---|
0 | seconds | 1970-01-01 00:00:00 | Unix epoch |
946684800 | seconds | 2000-01-01 00:00:00 | Known test value |
1704067200000 | milliseconds | 2024-01-01 00:00:00 | Millisecond check |
-1 | seconds | 1969-12-31 23:59:59 | Before the epoch |
Check numeric range. The Unix-second value for 2038-01-19 03:14:07 UTC is 2147483647. Older 32-bit signed storage may fail one second later.
Authoritative references: see the POSIX time rationale, RFC 3339 and the IANA Time Zone Database.
Frequently asked questions
If a result looks wrong, check the input unit and the time-zone basis first.
Are a Unix timestamp and UTC the same thing?
No. A Unix timestamp counts time from 1970-01-01 00:00:00 UTC, while UTC is the global time standard used to interpret that instant.
Can this converter detect seconds and milliseconds automatically?
Yes. Auto mode estimates seconds, milliseconds, microseconds or nanoseconds from the number of digits and shows the detected unit. Select the known source unit manually whenever possible.
What is the difference between 10-digit and 13-digit timestamps?
Around present-day dates, 10 digits usually means seconds and 13 digits usually means milliseconds. Milliseconds represent the same instant with 1,000 units per second.
Does Unix time count leap seconds?
Conventional POSIX Unix time does not count leap seconds as separate seconds, so this tool does not accept 23:59:60 as an ordinary calendar time.