Date and Time Format Converter
Description
Compare a moment across timezones on live analog clocks (World Clock), and auto-convert Unix timestamps, ISO 8601 strings, and dates to every format at once.
About Date and Time Format Converter
Compare a moment across timezones on live analog clocks, and convert between Unix timestamps, ISO 8601 strings, and human-readable dates. The World Clock shows any number of cities side by side — with day/night shading and a business-hours badge — while the Timestamp Converter auto-detects whether you pasted a Unix timestamp (seconds or milliseconds) or a date string and converts it to every format at once. Everything is computed entirely in your browser, so no dates or timestamps ever leave your device.
How to use
- In the World Clock, set a source timezone and either leave it live ("Now") or pick a fixed date & time — every clock card updates to show that same moment.
- Add or remove cities from the clock grid with the searchable timezone picker; each card shows the local time, date, GMT offset, and day/night and business-hours badges.
- In the Timestamp Converter, paste a Unix timestamp, an ISO 8601 string, or any date — it's auto-detected and converted to Unix (seconds/ms), ISO 8601, UTC, local time, and a relative ('in 3 hours') description.
- Use the copy button on any clock card or result row to copy that value for your code, tests, or API requests.
Examples
| Example | Input | Output |
|---|---|---|
| Unix epoch to ISO 8601 | 0 | 1970-01-01T00:00:00Z |
Frequently asked questions
What is a Unix timestamp?
A Unix timestamp is the number of seconds elapsed since the Unix epoch, which is 1970-01-01T00:00:00Z (midnight UTC on January 1, 1970). Many systems also use milliseconds, which is 1000 times larger for the same instant.
How does the converter tell seconds from milliseconds?
By digit count: Unix timestamps in seconds are 11 digits or fewer for realistic dates, while millisecond timestamps run to 13 digits. JavaScript's Date.now() returns milliseconds, whereas many backend languages use seconds, so this magnitude check is what the auto-detection relies on.
How are timezones handled in the World Clock?
Every clock card computes the same underlying instant in its own timezone, including DST — that's why two cities can show a different clock time and even a different calendar day ("+1 day") for the exact same moment.
Is my data sent to a server?
No. All parsing and conversion happen locally in your browser, so the dates, timestamps, and timezones you pick are never uploaded anywhere. The clock list you build is saved only on your own device.