Unix Timestamp Converter
Convert Unix timestamps to human-readable dates (local, UTC, ISO 8601) and back — with a live current-epoch clock. Detects seconds vs. milliseconds automatically.
Timestamp → date
Date → timestamp
How it works
Unix time counts the seconds elapsed since January 1, 1970, 00:00:00 UTC (the "epoch"). It's how most systems, databases, and APIs store instants in time, because a single integer is unambiguous across time zones.
Paste a timestamp and the converter shows the corresponding date three ways: in your local time zone, in UTC, and in ISO 8601 format. It detects the unit automatically — 10-digit values are read as seconds, 13-digit values as milliseconds (the JavaScript convention). The reverse direction works too: pick a date and time and get the timestamp in both units. A live clock at the top shows the current epoch second.
When to use
Debugging anything that logs epoch time: API responses, database rows, JWT exp/iat claims,
log files, cron schedules, cache expiry headers. Instead of mentally dividing by 86,400 or
firing up a REPL, paste the number and read the date.
The date → timestamp direction is just as common: building a query that filters "records after July 1st" against a column stored in epoch seconds, or crafting a test fixture with a specific expiry.
Practical examples
Reading a JWT expiry
A token carries "exp": 1751500800. Pasting it shows the exact local date and time the token
dies — no math, no time-zone guessing.
Milliseconds from JavaScript
Date.now() returned 1751500800000 (13 digits). The converter recognizes milliseconds
automatically and shows the same instant as the seconds version above.
Common mistakes
The seconds-vs-milliseconds mix-up is the classic: treating a millisecond value as seconds lands you tens of thousands of years in the future, and the reverse puts you in January 1970. The automatic detection here handles the common cases, but be careful in code — JavaScript uses milliseconds while most Unix APIs and databases use seconds.
Time-zone confusion is the other trap. A timestamp is absolute; only its representation changes with the zone. If a log says an event happened at "14:00", first find out whether that rendering was local or UTC — the underlying timestamp is the reliable reference.
Frequently asked questions
What is the Unix epoch?
The instant 1970-01-01 00:00:00 UTC, the zero point of Unix time. Timestamps are the count of seconds (or milliseconds) since then.
How does the tool know if my value is seconds or milliseconds?
By magnitude: values under 10^12 are treated as seconds, larger ones as milliseconds. Current dates have 10 digits in seconds and 13 in milliseconds, so the heuristic is unambiguous for contemporary timestamps.
What is the year 2038 problem?
Systems that store Unix time in a signed 32-bit integer overflow on 2038-01-19. Modern systems use 64-bit values, which postpone the issue by about 292 billion years.
Do timestamps have time zones?
No — a timestamp identifies an absolute instant. Time zones only apply when formatting it for humans, which is why this tool shows local, UTC, and ISO renderings of the same value.