Seconds or milliseconds?

If the absolute value is at least 100 billion, it is treated as milliseconds.

Which time zone for the picker?

Your browser’s local zone. Use the time zone converter for named IANA zones.

No. All conversion happens in this page.

Convert in both directions: paste epoch values from logs or pick a local moment for API timestamps. All processing stays in your browser.

Timestamp

Longer values are treated as milliseconds; shorter ones as seconds.

Result

Timestamp mode parses numbers as epoch time; date mode builds a local datetime and outputs Unix seconds and milliseconds.

Values with absolute magnitude at least 100 billion are read as milliseconds; smaller ones as seconds.

Unix time counts from midnight UTC on 1 January 1970. The picker uses your browser’s local time zone.

JavaScript dates cover roughly ±285616 years around 1970; extreme inputs may show as invalid.

Seconds or milliseconds?: If the absolute value is at least 100 billion, it is treated as milliseconds.
Which time zone for the picker?: Your browser’s local zone. Use the time zone converter for named IANA zones.
Is data sent online?: No. All conversion happens in this page.
Negative timestamps?: Yes, for times before 1970.