Date.now().Z.+10:00.All four describe the same instant. Only the wall-clock display changes.
Some inputs are too long to fit in the URL.
Anyone with this link can read the values it contains. Do not use it for sensitive data.
A Unix timestamp (also called epoch time) is the number of seconds since 1970-01-01 00:00:00 UTC. It's compact and timezone-free, which makes it ideal for storing and comparing moments in code and databases.
ISO 8601 is the human-and-machine-friendly text format for the same instant. It reads YYYY-MM-DDThh:mm:ssZ, where the trailing Z means UTC and an offset like +05:30 shifts it into a local timezone. For example, epoch 1700000000 is 2023-11-14T22:13:20Z in ISO 8601.
Paste the ISO string into the input and the Unix timestamp appears in both seconds and milliseconds. The direction is detected from what you paste, so there is no mode to switch. The one input that needs care is an all-digits date: 20240301 is valid ISO 8601 basic format, but anything made only of digits is read as an epoch value, so write that date as 2024-03-01 to have it treated as a date.
The part that trips people up is the timezone designator at the end. An ISO 8601 string is only unambiguous if it carries one, and it changes the answer: 2024-03-01T09:30:00+05:30 and 2024-03-01T04:00:00Z are the same instant, so both give 1709265600. Leave the designator off and the rules change under you: a full date and time is read in your browser's own timezone, while a bare date such as 2024-03-01 is read as UTC. That split is why the same text can produce different timestamps on two machines.
| ISO 8601 input | Seconds | Milliseconds |
|---|---|---|
| 2023-11-14T22:13:20Z | 1700000000 | 1700000000000 |
| 2026-01-15T09:30:00Z | 1768469400 | 1768469400000 |
| 2024-03-01T09:30:00+05:30 | 1709265600 | 1709265600000 |
| 2023-11-14T22:13:20.500Z | 1700000000 | 1700000000500 |
Fractional seconds are kept in the milliseconds column and dropped from the seconds column, so .500 becomes a trailing 500 in one and nothing in the other. Reach for milliseconds when you are feeding a JavaScript Date, and seconds for most database columns and APIs.
| Unix timestamp | ISO 8601 (UTC) | What it is |
|---|---|---|
| 0 | 1970-01-01T00:00:00Z | The Unix epoch (time zero) |
| 1000000000 | 2001-09-09T01:46:40Z | One billion seconds |
| 2147483647 | 2038-01-19T03:14:07Z | The 32-bit "Year 2038" limit |
Pick an IANA timezone to see the same instant in local time. Common ones: Asia/Kolkata for IST, America/New_York for Eastern, America/Los_Angeles for Pacific, Europe/London for GMT/BST, and UTC itself. The zoned ISO output carries the correct offset, including daylight saving where it applies.