Unix Timestamps, ISO 8601 and Time Zones Explained

Auto-detect Unix seconds or milliseconds and convert among local time, UTC, ISO 8601 and multiple IANA zones with relative time.

What to know before you start

A timestamp is an instant, not a city time zone. Historical/future local display depends on IANA time-zone rules and daylight-saving changes.

Recommended workflow

Use a Unix timestamp when you need a compact instant, and ISO 8601 when human-readable date/time plus an offset is useful.
Treat a timestamp as UTC-based instant data; do not attach a fixed local offset by memory.
For local scheduling, store or communicate the IANA time zone separately when future DST rules matter.

How to check the result

Recheck the result against the original input and the rule you intended to apply. A timestamp is an instant, not a city time zone. Historical/future local display depends on IANA time-zone rules and daylight-saving changes.

Common mistakes

Common failures come from wrong units, ambiguous assumptions, changing the rule after seeing a result, or using a quick browser workflow where a regulated or specialist process is required.

Frequently asked questions

Why are some Unix timestamps 10 digits and others 13?

Modern timestamps in seconds are commonly around 10 digits, while milliseconds are commonly around 13. Always confirm the unit rather than relying only on length.

Does a Unix timestamp contain a time zone?

No. It identifies an instant relative to UTC; a time zone is applied only when displaying that instant as local time.

Unix Timestamp Converter