Unix timestamp, ISO date, timezone and batch converter
Convert Unix seconds, milliseconds, microseconds, nanoseconds and readable date strings into UTC, local time, ISO 8601, RFC 2822, SQL format and timezone views. Batch-convert log timestamps, inspect JWT date claims and avoid the classic seconds-versus-milliseconds mistake.
Conversion runs in your browser. Unix time is always based on UTC; timezone formatting changes the display, not the instant.
Timestamp conversion is mostly about avoiding wrong assumptions
Unix timestamps look simple because they are just numbers, but they create many production bugs. Some systems use seconds, JavaScript uses milliseconds, databases may store microseconds, and event pipelines sometimes log nanoseconds. A 10-digit value and a 13-digit value can point to the same instant if one is seconds and the other is milliseconds. Reading that value in the wrong unit can move a date by decades.
This timestamp converter is made for debugging logs, JWT claims, APIs, schedulers, backups and database rows. It auto-detects common numeric lengths, supports explicit seconds, milliseconds, microseconds and nanoseconds, parses ISO date strings, compares UTC with named timezones, calculates relative distance from now, and converts a batch of mixed values into CSV for tickets or incident notes.
How to read timestamps safely
Start by identifying the unit. Unix seconds are often 10 digits for modern dates. Unix milliseconds are often 13 digits. Microseconds and nanoseconds are longer and may be too precise for normal JavaScript date handling, so the visible date is based on the millisecond portion. Then keep storage and display separate: store UTC instants, format them for the user at the edge, and mention the timezone whenever a human schedule or deadline is involved.
- Unix seconds are common in JWT
exp,nbfandiatclaims. - Unix milliseconds are common in JavaScript, browser logs and many APIs.
- ISO 8601 is usually the cleanest human-readable interchange format.
- Timezone views explain what the same instant means in Paris, UTC, New York or Tokyo.
- Batch conversion helps during incident review when logs contain mixed formats.
Common timestamp debugging examples
If a token expires immediately, decode the JWT and convert the exp claim as Unix seconds. If a cron job appears to run at the wrong hour, compare the server timezone and the human timezone. If a log date looks like 1970 or far in the future, check whether milliseconds were treated as seconds or seconds were treated as milliseconds. If two regions disagree on a date, compare the same UTC instant in both timezones before changing application logic.
Common questions
Is Unix time affected by timezone?
No. Unix time counts from the UTC epoch. Timezones only change how the instant is displayed to humans.
Why do JavaScript timestamps have 13 digits?
JavaScript Date values are milliseconds since the Unix epoch, while many APIs use seconds.
Can I convert nanoseconds exactly?
The tool can detect and scale nanosecond timestamps for date display, but browser dates display millisecond precision.
How do I convert a Unix timestamp to a date?
Paste the epoch value into the tool. It auto-detects whether the number is in seconds, milliseconds, microseconds or nanoseconds, then shows the matching local time, UTC and ISO 8601 string.
What is the Unix epoch?
The Unix epoch is 00:00:00 UTC on 1 January 1970. Unix time is the count of seconds elapsed since that instant, ignoring leap seconds, which is why it is a stable reference for storing and comparing moments across systems.
What is the year 2038 problem?
Systems that store Unix time in a signed 32-bit integer overflow on 19 January 2038 and wrap to a negative date. The fix is to store time in a 64-bit value, which every modern language and database now does by default.
