Value Converter Tools
Unix Timestamp Converter
Convert Unix timestamps to readable ISO 8601 dates, or turn timezone-aware ISO dates into seconds or milliseconds since the Unix epoch.
✓ Every tool runs in your browser. We do not upload your input or output.
Keyboard shortcuts
Ctrl/⌘ + Enter: process
Ctrl/⌘ + Shift + F: full screen
Esc: exit full screen
Ctrl/⌘ + F in editor: search
How to use
- Enter a decimal Unix timestamp or a complete ISO 8601 date with a timezone.
- Choose Timestamp to date or Date to timestamp, then select seconds or milliseconds.
- Read the result and verify the unit and timezone before using it.
- Copy or download the converted value for a log, API request, or test fixture.
Examples
Read a log timestamp
With seconds selected, the epoch value becomes a UTC ISO date.
1700000000
2023-11-14T22:13:20.000Z
Create a millisecond timestamp
Date to timestamp with milliseconds selected produces an integer suitable for JavaScript time APIs.
2023-11-14T22:13:20Z
1700000000000
Check time values without guessing the unit
Unix time is convenient for storage and logs, but a value like 1700000000 is difficult to read at a glance. Paste it into the workspace and choose seconds to see the matching UTC date. If the value has 13 digits and came from a JavaScript time API, milliseconds may be the correct unit. A mistaken unit can move a date by decades, so check the source system before copying the result.
The reverse direction is useful when constructing test fixtures or comparing an API response with a human-readable event time. Enter a complete ISO 8601 value such as 2023-11-14T22:13:20Z, choose Date to timestamp, and select the unit your destination expects. A timezone offset is required. The tool checks calendar fields such as month, day, and hour rather than silently normalizing a mistyped date.
Read the timezone explicitly
ISO output ends with Z, which means UTC. An ISO input with +02:00 is converted to the same instant in UTC before the timestamp is calculated. The local timezone of your computer does not change this conversion. Include an explicit offset when you paste a date from a log or API, especially near midnight when a timezone mistake can change the calendar day.
Fractional ISO seconds are accepted to millisecond precision. A seconds timestamp can also contain a decimal fraction. Very large values outside the JavaScript Date range produce a clear error. This tool processes your input in a browser worker, and the value stays on your device. The workspace keeps a fixed height while you review long lists or notes, although this converter processes one value at a time.
Frequently asked questions
What is a Unix timestamp?
It is elapsed time since 1970-01-01T00:00:00Z. This tool accepts seconds or milliseconds, depending on the unit selected.
Why does my result show Z?
Z means UTC. ISO output uses UTC even when the input date includes a different timezone offset.
Can the input date omit a timezone?
No. Enter Z or an offset such as +02:00 so the instant is unambiguous.
Are fractional seconds supported?
Yes. ISO inputs can include up to three fractional digits; decimal Unix seconds are also accepted.
What happens outside the supported date range?
The tool reports an error instead of producing an invalid date. JavaScript Date bounds the supported range.