A ten-digit value is seconds
Input
1750000000
Result
2025-06-15T15:06:40.000Z
This is the form used by JWT exp and iat claims, Unix date, and most SQL epoch functions.
Time Tools
Unix Timestamp Converter
Convert Unix timestamps to dates and turn dates back into seconds or milliseconds.
ISO: 2026-08-12T22:47:54.000Z
Local: Aug 12, 2026, 10:47:54 PM
Seconds: 1786574820
Milliseconds: 1786574820000
Understand the format
How Unix Timestamp Converter works
Unix time counts seconds since 1970-01-01T00:00:00Z, which gives every machine one unambiguous instant to agree on before time zones enter the picture.
One number, no time zone
A Unix timestamp is the number of seconds elapsed since the epoch, midnight UTC on 1 January 1970. It carries no time zone, no daylight-saving rule, and no calendar formatting. That is its entire value: two servers on opposite sides of the world computing 1750000000 mean precisely the same instant. A time zone only becomes relevant when the number is rendered for a person.
The definition deliberately ignores leap seconds. A Unix day is always exactly 86,400 seconds, so a leap second is absorbed rather than counted. This keeps arithmetic simple, at the cost of the count drifting slightly from true astronomical time.
Seconds, milliseconds, and the 2038 limit
The most common bug in this area is a unit mismatch. Unix tooling, JWT claims, and most database functions use seconds; JavaScript Date.now, Java System.currentTimeMillis, and many log pipelines use milliseconds. A quick check by digit count settles it: a present-day timestamp in seconds has 10 digits, in milliseconds it has 13. Feed milliseconds into a seconds-based parser and you land somewhere around the year 57000; feed seconds into a milliseconds-based one and you land in January 1970.
The second limit worth knowing is the year 2038 problem. A signed 32-bit integer overflows at 2147483647 seconds, which is 19 January 2038. Systems that still store time in a 32-bit field wrap around to 1901 at that point. Modern platforms use 64-bit values, but embedded devices, old file formats, and legacy database columns can still be affected.
Step by step
How to use Unix Timestamp Converter
- Paste a numeric timestamp into the left field to convert it into an ISO 8601 string and a readable local time.
- Values above one trillion are treated as milliseconds, so both units are accepted without conversion.
- Use the date and time field on the right to go the other way and read the value in both seconds and milliseconds.
- When sharing a converted time with colleagues, quote the ISO form so the time zone is explicit.
Conversion uses the browser Date and Intl APIs. Timestamps you paste are not transmitted, and only your device time zone influences the local rendering.
Worked examples
Unix Timestamp Converter examples explained
The 32-bit signed limit
Input
2147483647
Result
2038-01-19T03:14:07.000Z
One second later, a signed 32-bit time_t wraps to December 1901. Timestamps near this value in test data are usually a deliberate boundary check.
Reference
Recognising a timestamp by its shape
| Digits | Unit | Example | Interpretation |
|---|---|---|---|
| 10 | Seconds | 1750000000 | Present day. The standard Unix time unit. |
| 13 | Milliseconds | 1750000000000 | Present day. JavaScript and JVM default. |
| 16 | Microseconds | 1750000000000000 | Common in tracing systems and Postgres internals. |
| 9 or fewer | Seconds, historical | 946684800 | Dates before 2001. 946684800 is 2000-01-01T00:00:00Z. |
| Negative | Seconds before 1970 | -86400 | 1969-12-31T00:00:00Z. Valid, but rejected by some parsers. |
Practical Guide
How teams use Unix Timestamp Converter
Common use cases
- Read log times during incident response and release verification.
- Confirm whether an expiry value is expressed in seconds or milliseconds.
- Turn scheduled job times into a form the rest of the team can review quickly.
Checks before trusting the result
- Verify the digit length before trusting a conversion; seconds and milliseconds are easy to confuse.
- Be explicit about the time zone whenever you share a converted date.
- Compare converted times against the source system clock when expiry logic is involved.
Troubleshooting
Common mistakes and how to fix them
- A token expires immediately or never.
- Check the unit. A JWT exp written in milliseconds is read as a date far in the future; one written in seconds by a millisecond-based library expires instantly.
- A daily job appears to run an hour early or late twice a year.
- The schedule is being evaluated in local time across a daylight-saving transition. Schedule in UTC and convert for display only.
- A date renders differently for two people looking at the same record.
- They are in different time zones. Store the instant, render with an explicit zone, and put the offset in the string you share.
FAQ
Unix Timestamp Converter questions, answered
Why 1 January 1970?
It was a convenient recent round date when Unix time was defined in the early 1970s. There is nothing special about it beyond convention, and other systems use different epochs.
Does Unix time account for leap seconds?
No. Every day is treated as exactly 86,400 seconds, so leap seconds are skipped or repeated depending on the platform. For interval arithmetic at second resolution this is almost never a problem.
Can a Unix timestamp be negative?
Yes. Negative values represent instants before 1970. They are legal, but plenty of libraries and databases handle them poorly, so historical dates are often better stored as dates rather than timestamps.
What is ISO 8601 and why prefer it in messages?
It is the standard textual format, for example 2025-06-15T15:06:40Z. Unlike a raw number it is readable, and unlike a local date string it states its offset, with Z meaning UTC.
Which local time is shown here?
The time zone configured on your device. The ISO line is always UTC, so use that one whenever two people need to be certain they are discussing the same instant.
Go deeper
Specifications and guides
- Unix Time, Time Zones, and Expiry Bugs — Why tokens expire immediately, jobs run twice a year at the wrong hour, and two people see different dates for one record.
- JWT Claims, Expiration, and Safe Token Inspection — What to inspect in a JWT and what not to trust when you are debugging auth.