Unix Timestamp Converter
Convert Unix seconds or milliseconds to dates, and ISO dates back to Unix time.
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When to use unix timestamp converter
- Inspect API event times.
- Understand JWT exp and iat values, which normally use seconds.
How it works
Unix time counts seconds since 1970-01-01T00:00:00Z. JavaScript Date uses milliseconds. UTC is shown explicitly and the local rendering uses your browser’s timezone.
Supported inputs and limits
A timezone is required for date input to avoid guessing. Leap seconds are not represented. Millisecond precision is the maximum, and sub-millisecond values are truncated.
Common questions
Why is my date decades away?
Check the unit. Passing milliseconds as seconds changes the value by a factor of 1,000.
What does the local result use?
Your browser’s current timezone. The UTC output is independent of that setting.
Methodology reviewed 2026-09-09. Processing details and test approach.