How to convert a Unix timestamp
- Paste a timestamp into the left box,
1751554800for seconds or1751554800000for milliseconds. Conversion happens live, so you never press a button. - Going the other way? Type a date instead, an ISO 8601 value like
2026-07-03T15:00:00Z, or a plain phrase likeJuly 3, 2026, and read off the epoch equivalents. - The right pane shows every format at once: Unix seconds, milliseconds, ISO 8601 in UTC, the same moment in your local time zone, and a relative phrase such as "in 3 days" or "2 hours ago".
- Click Use current time to drop in the epoch for this exact moment, then Copy output to take all the formats with you.
Seconds vs milliseconds, the bug that bites everyone
Unix time counts from a single fixed instant, midnight UTC on 1 January 1970, known as "the epoch", and it is the backbone of how computers store moments: log lines, database columns, cron schedules, API responses and JWT exp claims all speak it. The trap is the unit. JavaScript's Date.now() returns milliseconds, while Unix tools, most REST APIs and JWTs use seconds. Feed a seconds value into something expecting milliseconds and your date lands in January 1970; do the reverse and you jump to the year 57519. This converter reads the magnitude of the number and picks the unit for you, so a 10-digit (seconds), 13-digit (milliseconds) or 16-digit (microseconds) value all decode to the date you actually meant, a fast way to sanity-check which unit an unfamiliar API is handing you.
UTC vs local time, and why the raw number never changes
A Unix timestamp is always UTC, it has no time zone baked in, which is exactly why systems like it: the same integer means the same instant in London, Tokyo and San Francisco. The time zone only enters when you render that instant for a human. That is why this tool shows two lines: the ISO 8601 value in UTC (ending in Z) for logs and APIs, and the same moment translated into your browser's local zone for a human reading. If a colleague three zones away pastes the identical timestamp, their raw seconds match yours exactly while their local line reads a different wall-clock time. Watch out for two related gotchas: daylight saving shifts the local rendering by an hour twice a year without touching the underlying number, and a bare date like 2026-07-03 is interpreted at midnight, so it can appear to land on the previous day once converted to a zone behind UTC.
Frequently asked questions
What is a Unix timestamp?
The number of seconds elapsed since 1 January 1970 at 00:00 UTC. A single integer is unambiguous across time zones and trivial to compare or subtract, which is why databases, APIs and log formats prefer it over written-out dates.
How do I tell seconds from milliseconds?
Around the present day a seconds value is 10 digits and a milliseconds value is 13 digits, three extra zeros on the end. The converter detects the unit from the number's magnitude automatically, and even 16-digit microsecond values decode correctly.
Can I convert a date back to a timestamp?
Yes. Paste an ISO 8601 string like 2026-07-03T15:00:00Z or a plain date like July 3, 2026 and you immediately get both the Unix seconds and milliseconds. A date with no time is treated as midnight.
Is the timestamp in my time zone or UTC?
The raw Unix number is always UTC and carries no zone. The tool shows the ISO 8601 value in UTC and, separately, the same instant converted to your browser's local time zone so both audiences are covered.
Why does my date look a day off?
Usually a UTC-versus-local mismatch. A value near midnight UTC falls on the previous calendar day once shown in a zone behind UTC (the Americas), and daylight saving can nudge the local rendering by an hour, while the underlying number stays exactly the same.
What is the year 2038 problem?
Systems that store Unix time in a signed 32-bit integer overflow on 19 January 2038, wrapping to a negative number and a 1901 date. Modern 64-bit systems, and this tool, push that limit billions of years out, so timestamps far beyond 2038 convert fine. Handy alongside the JWT Decoder for checking token expiry.