Convert epoch values with explicit units and offsets

How to use the workspace

1. Choose epoch-to-date or ISO-to-epoch.
2. Select the epoch unit. ISO input must include Z or an explicit offset.
3. Set the display timezone, convert, and compare seconds, milliseconds, ISO and local representations.

A concrete starting point

1704067200 seconds
1704067200000 milliseconds
2024-01-01T00:00:00Z
These describe the same instant.

A different display timezone changes the local clock reading, not the underlying instant.

Read the result carefully

Fractional seconds can carry millisecond precision. Milliseconds must be integers. Negative epoch values describe instants before the epoch. The output includes the timezone offset to make the local representation unambiguous.

Common mistakes to avoid

• A large integer is not evidence of a particular unit; the tool never guesses.
• A naive local datetime without an offset can be ambiguous near DST transitions and is not accepted.
• More than three fractional second digits would imply precision this tool does not preserve.

Limits & privacy

ISO instants require offsets and at most millisecond precision. Timezones must be supported IANA identifiers. Local-only; the current-time shortcut runs only when clicked.