What does this tool do
The Timestamp Converter converts Unix timestamps (seconds or milliseconds) and date strings to multiple formats. Enter a number or an ISO 8601 / RFC 2822 string, and get Unix seconds, milliseconds, ISO 8601, RFC 2822, and a human-readable date. Auto-detects seconds vs milliseconds for numeric input. Built for developers who work with timestamps and APIs.
How to use it
- Enter input — Type a Unix timestamp (e.g. 1709251200 or 1709251200000) or a date string (e.g. 2024-03-01T12:00:00Z).
- View outputs — Unix seconds, milliseconds, ISO 8601, RFC 2822, and human-readable format appear.
- Use any format — Copy the format you need (e.g. for API payloads or logs).
- Reverse — Paste an ISO or RFC 2822 string to get the Unix timestamp.
How it works
Numeric input: Values < 1e12 are treated as seconds (covers 1970–33658); values ≥ 1e12 as milliseconds. String input: Passed to Date.parse, which supports ISO 8601, RFC 2822, and common formats. Outputs are generated from a single UTC millisecond value: ISO 8601 via toISOString(), RFC 2822 with explicit +0000 offset, human-readable via Intl.DateTimeFormat. Out-of-range timestamps return an error.
All computation runs entirely in your browser. No data is sent to any server.
Use cases & examples
- API development — Convert between formats for request/response.
- Log analysis — Decode Unix timestamps from logs.
- Database — Translate stored timestamps to human dates.
- Debugging — Verify date parsing and timezone handling.
- Documentation — Generate example timestamps for docs.
Example
1709251200(seconds) → 2024-03-01T12:00:00.000Z1709251200000(milliseconds) → same date2024-03-01 12:00:00→ Unix timestamp + all formats
Limitations & known constraints
- UTC output — Outputs are in UTC; no timezone conversion.
- Range — Timestamps outside JavaScript Date range may fail.
- Auto-detect — 1e12 threshold for seconds vs ms; ambiguous for values near that.
- String parsing — Depends on
Date.parse; non-standard formats may fail.