Unix Timestamp Converter - Epoch to Date & Back

About the Unix Timestamp Converter

Computers usually store moments in time as a single number: the Unix timestamp, also called epoch time or POSIX time. It counts the seconds that have passed since 00:00:00 UTC on 1 January 1970, the Unix epoch. Timestamps appear in databases, log files, APIs, cookies, file systems and spreadsheets exported from software, and they are unreadable to people — 1790000000 means nothing at a glance.

This Unix timestamp converter turns a timestamp in seconds or milliseconds into a readable date and time in UTC, in ISO 8601 format and in any time zone you choose. It also works in reverse, turning a UTC date and time into a timestamp. It detects milliseconds automatically and tells you whether a timestamp is beyond the year 2038 limit of older 32-bit systems.

How to Use the Unix Timestamp Converter

Choose Timestamp to date or Date to timestamp.

For a timestamp, paste the number. Ten digits are read as seconds; 12 or more as milliseconds.

For a date, enter the UTC date and optionally the UTC time.

Choose a time zone to see the local time as well.

How the Conversion Works

  timestamp (seconds)  = days since 1970-01-01 × 86,400 + seconds into the day
  timestamp (ms)       = seconds × 1,000

  date = 1970-01-01 00:00:00 UTC + timestamp seconds

Unix time ignores leap seconds: every day is treated as exactly 86,400 seconds, which keeps the arithmetic simple.

Step-by-Step Examples

1790000000 to a date.

  1,790,000,000 ÷ 86,400 = 20,717 days + 51,200 seconds
  20,717 days after 1 January 1970 = 21 September 2026
  51,200 s = 14 h 13 min 20 s
  → Monday 21 September 2026, 14:13:20 UTC
  → 19:13:20 in Pakistan (UTC+5)

29 September 2026, 12:00:00 UTC to a timestamp.

  days since 1970-01-01 = 20,725
  20,725 × 86,400 + 12 × 3,600 = 1,790,683,200

Seconds or Milliseconds?

Unix and Linux systems, PHP, Python's time module and most databases use seconds. JavaScript's Date.now(), Java's System.currentTimeMillis() and many web APIs use milliseconds. A current timestamp in seconds has 10 digits; in milliseconds, 13. If a converted date lands in the year 58,000 or so, you have almost certainly treated milliseconds as seconds. The converter checks the length automatically.

Time Zones

A Unix timestamp is the same all over the world — it identifies a single instant, not a local clock reading. Only its display depends on the time zone. The same timestamp 1790000000 is 14:13 UTC, 15:13 in London (summer time), 19:13 in Karachi and 10:13 in New York. When debugging, remember that many tools display timestamps in the computer's local zone, so always check which zone a displayed time is in.

The Year 2038 Problem

Older systems store timestamps as signed 32-bit integers, whose maximum value is 2,147,483,647. That moment is 03:14:07 UTC on Tuesday 19 January 2038. One second later the number overflows to a large negative value, which such systems read as a date in December 1901. It is a similar problem to the Year 2000 bug. Modern operating systems, databases and languages use 64-bit timestamps, which will not overflow for about 292 billion years, but embedded devices and old file formats may still be affected.

Negative Timestamps

Dates before 1970 have negative timestamps. −86,400 is 00:00 UTC on 31 December 1969, and the Moon landing at 20:17 UTC on 20 July 1969 is −14,182,980. Most modern systems handle negative timestamps correctly, but some older software does not, which can cause problems with historical dates such as birth dates.

Timestamps in Spreadsheets

Spreadsheets store dates differently, as a count of days since a starting date — 1 January 1900 in Excel's usual system. To turn a Unix timestamp in seconds into a spreadsheet date, divide it by 86,400 and add the spreadsheet's value for 1 January 1970, which is 25,569 in Excel: =A1/86400+25569, then format the cell as a date and time. For milliseconds, divide by 86,400,000 instead. The result is in UTC, so add or subtract hours for your local zone. Going the other way, subtract 25,569 and multiply by 86,400. It is worth checking one converted value against this converter before relying on a whole column.

Common Places You Will See Timestamps

Logs: server and application logs often record events as timestamps. APIs: created and updated times in JSON responses. Databases: columns storing times as integers. Cookies and tokens: expiry times in web cookies and JSON Web Tokens use seconds since the epoch. Files: modification times on Unix file systems.

Understanding Your Result

The headline gives the date and time in UTC, or the timestamp.

The timestamp line gives the value in seconds and milliseconds.

The UTC line gives the full date with weekday.

The ISO 8601 line gives the standard machine-readable form.

The in your zone line gives the local time in the zone you chose.

The worth knowing line says how the input was read and checks the 2038 limit.

When Should You Use This Calculator?

Use it to read timestamps in logs, databases and API responses.

Use it to create timestamps for testing and configuration.

Use it to check token and cookie expiry times.

Use it to convert between UTC and local time for debugging.

Common Mistakes

Treating milliseconds as seconds. The date lands tens of thousands of years ahead.

Assuming a timestamp is in local time. It is always UTC-based.

Entering a local date when converting to a timestamp. Convert to UTC first.

Ignoring the 2038 limit on old systems. Check the storage type.

Pasting a timestamp with separators. Commas and spaces are removed, but decimal points are not accepted.