Utilix
Date & time·Epoch Cron

Unix Timestamp Converter

Convert Unix epoch timestamps to ISO 8601 dates (and back) in any timezone. Auto-detects seconds, milliseconds, microseconds, or nanoseconds.

Input

Result

Enter a value for direction to see your result.

How it works

Converts between Unix epoch timestamps and human-readable ISO 8601 dates. Auto-detects whether the input is in seconds, milliseconds, microseconds, or nanoseconds, and renders the result in any timezone (or local browser time).

Formula

ISO_date = epoch_unix / 1000^k + 1970-01-01T00:00:00Z

epoch_unix
Unix timestamp value entered
k
0 for seconds, 1 for ms, 2 for µs, 3 for ns

Step by step

  1. 01Pick the direction: timestamp → date, or date → timestamp.
  2. 02If converting to a date, choose the unit (or leave it on auto-detect, which guesses by magnitude).
  3. 03Auto-detect rule: |t| ≥ 1e16 → ns, ≥ 1e13 → µs, ≥ 1e10 → ms, otherwise seconds.
  4. 04If converting from a date, type any ISO-8601 string (a Z suffix means UTC).
  5. 05The output renders the moment in the chosen display timezone with weekday and a 'how long ago' relative label.

Examples

Seconds → ISO (1700000000)

1,700,000,000 seconds since the epoch is exactly 22:13:20 UTC on 14 November 2023. Multiplied by 1000 gives 1.7e12 ms.

Inputs

Direction:
to-date
Unix timestamp:
1700000000
Unit:
s
Display timezone:
UTC

Result

ISO 8601 (UTC):
2023-11-14T22:13:20.000Z
Unix milliseconds:
1700000000000
Detected unit:
seconds

Milliseconds auto-detected (1700000000000)

Magnitude 1.7e12 → milliseconds branch. Same instant as the seconds example, just at 1000× scale.

Inputs

Direction:
to-date
Unix timestamp:
1700000000000
Unit:
auto
Display timezone:
UTC

Result

ISO 8601 (UTC):
2023-11-14T22:13:20.000Z
Unix seconds:
1700000000
Detected unit:
milliseconds (auto-detected)

ISO → seconds (epoch 0)

The Unix epoch itself: 1 January 1970 at midnight UTC.

Inputs

Direction:
to-timestamp
Date/time (ISO 8601):
1970-01-01T00:00:00Z
Display timezone:
UTC

Result

Unix seconds:
0
Unix milliseconds:
0
ISO 8601 (UTC):
1970-01-01T00:00:00.000Z
Note: All conversions go through UTC internally — the display timezone only affects the human-readable preview. Negative timestamps are supported and represent dates before 1970-01-01.

Frequently asked questions

What is a Unix timestamp?

A Unix timestamp (or epoch time) is the number of seconds that have elapsed since 1 January 1970 at 00:00:00 UTC, ignoring leap seconds. It is the most common way to store an absolute moment in time across systems.

How do I tell if my number is in seconds or milliseconds?

A timestamp in seconds for a date around 2024 has 10 digits (e.g. 1700000000). The same instant in milliseconds has 13 digits. Auto-detect uses this magnitude rule, but you can override it manually.

Why does my timestamp show a different time than expected?

Timestamps are timezone-agnostic — they are just a count of seconds since the UTC epoch. The display timezone in this tool only affects the readable label; the underlying instant is the same.