Unix Timestamp Converter
Convert Unix timestamps in seconds or milliseconds to human-readable dates in UTC, local time, or any timezone. Convert dates back to Unix time and copy ISO 8601, RFC 2822, and relative time.
Current Unix time
Live · updates every second— ms/—
Asia/Shanghai
Choose the timezone used to display or interpret the date. Named zones use the browser’s IANA timezone database.
Seconds or milliseconds. Auto-detect uses a 100 billion threshold.
Conversions update as you type. Dates use your browser’s Intl and IANA timezone data.
Under the hood
How it works
No black box: every transformation on this page is a documented browser API running on your device.
Unix time is counted from 00:00:00 UTC on 1 January 1970. It is timezone-independent; only its human-readable representation changes with a timezone.
- 01
Parse the value
The converter detects whether a bare number is in seconds or milliseconds, then validates it against JavaScript's supported date range (−8.64 × 10¹⁵ ms to +8.64 × 10¹⁵ ms).
- 02
Resolve the timezone
Dates are formatted with the browser's Intl API. Named timezones use the IANA database, including daylight-saving transitions and historical offsets.
- 03
Format every representation
One instant is rendered as ISO 8601, RFC 2822, UTC, local time, your chosen zone, and a human relative phrase. Nothing is sent to a server.
Common questions
Frequently asked
Short answers about how timestamp works and where its limits are.
Should I use seconds or milliseconds?
Unix time is traditionally measured in seconds. JavaScript, Java, and many APIs use milliseconds. The auto mode treats values of 100 billion or more as milliseconds, but you can override the unit at any time.
Why does the local time differ from UTC?
UTC is a fixed global reference. Local time applies your device's timezone offset, which may include daylight saving time. The timezone selector lets you preview any IANA zone independently of your device.
What is the valid timestamp range?
JavaScript dates can represent roughly 271,821 years before and after the Unix epoch, from −8,640,000,000,000,000 to 8,640,000,000,000,000 milliseconds. Values outside that range are rejected instead of silently overflowing.
Are fractional timestamps supported?
The converter accepts whole seconds or whole milliseconds. Fractional values are rejected to avoid hiding precision loss. Use milliseconds when you need sub-second accuracy.
All processing happens locally in your browser.
Your tool input is never uploaded. Google AdSense supports the site and may use cookies for advertising.