Unix timestamp converter

Converts between Unix timestamps and dates - seconds, milliseconds, UTC, local time, and ISO 8601.

1 · Timestamp to date

2 · Date to timestamp

All conversion happens in your browser. Large values use BigInt to avoid JavaScript floating-point precision loss.


What this does

Converts a timestamp (seconds, milliseconds, or microseconds - truncated to millisecond precision, since JavaScript Date has no finer resolution) to UTC, local time, ISO 8601 and a relative-time description, and converts a picked date back to seconds and milliseconds. A "use current time" button is deliberate rather than auto-refreshing, so the displayed value stays stable while you read it.

Precision handled correctly

Large timestamp values are parsed with BigInt rather than a plain JavaScript number, avoiding the silent precision loss that affects values beyond 2^53.

Privacy

All conversion happens in your browser - nothing is sent to a server.

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