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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