How to use the timestamp converter
- Paste a Unix timestamp on the left — it auto-detects seconds vs milliseconds.
- Or pick a date and time on the right to get the timestamp.
- The live current timestamp sits at the top, ready to copy.
What a Unix timestamp actually is
A Unix timestamp (also called epoch time or POSIX time) is simply the number of seconds that have passed since 1 January 1970 at 00:00:00 UTC — the "Unix epoch". Because it's a single number in UTC with no time zone or formatting attached, it's unambiguous, easy to compare and easy to store, which is why databases, APIs and log files use it constantly.
Seconds vs milliseconds — the usual gotcha
Unix time is traditionally in seconds, but JavaScript's Date.now() and many APIs return milliseconds — a number 1,000× larger. Feed a millisecond value into something expecting seconds and you'll land tens of thousands of years in the future. A quick sanity check: a current timestamp in seconds is 10 digits; in milliseconds it's 13. This tool detects the length and handles both automatically.
Benefits
- Converts both ways — timestamp to date and date to timestamp.
- Auto-detects seconds versus milliseconds so you cannot mix them up.
- Shows local time, UTC, ISO 8601 and a plain-English relative time.
- Live current timestamp at the top, ready to copy.
Limitations to know
- It converts and formats time — it does not do date arithmetic.
- Timestamps carry no time zone by definition; the local view uses your device setting.
- Extremely large values outside JavaScript date range cannot be represented.
Common mistakes to avoid
- Feeding a millisecond value into something expecting seconds (or the reverse) — a 1000× error.
- Assuming a timestamp is in local time; Unix time is always UTC.
- Storing timestamps in a signed 32-bit field, which overflows in January 2038.
Alternatives
To compare times across cities use the Time Zone Converter; to count days use Days Between Dates.
Last updated: August 2026 · Reviewed by the AI Toolbox editorial team.
Frequently asked questions
Seconds or milliseconds — which do I have?
10 digits is seconds, 13 digits is milliseconds. The converter detects it for you.
Do timestamps have a time zone?
No — a Unix timestamp is always UTC. Time zones only appear when you format it for display, which is why both local and UTC are shown here.
What is the year 2038 problem?
Systems storing the timestamp in a signed 32-bit integer overflow on 19 January 2038. Modern 64-bit systems aren't affected.
Can I use negative timestamps?
Yes — negative numbers represent dates before 1970 and are handled correctly.