Timestamp Converter

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. Choose a display timezone (Local, UTC, or common IANA zones) so ISO 8601 and human-readable outputs align on the same clock time. Auto-detects seconds vs milliseconds for numeric input. Built for developers who work with timestamps and APIs.

How to use it

1. Enter input — Type a Unix timestamp (e.g. 1709251200 or 1709251200000) or a date string (e.g. 2024-03-01T12:00:00Z).
2. Select display timezone — Choose Local (browser), UTC, or a common zone (e.g. Asia/Ho_Chi_Minh, America/New_York). ISO 8601 and human-readable formats use this zone.
3. View outputs — Unix seconds, milliseconds, ISO 8601, RFC 2822, and human-readable format appear.
4. Use any format — Copy the format you need (e.g. for API payloads or logs).
5. 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. Display timezone: When UTC or Local, ISO 8601 uses toISOString() or local formatting; when a non-UTC zone is selected, ISO 8601 includes the offset (e.g. 2026-03-01T19:00:00+07:00) so human-readable and ISO 8601 show the same clock time. RFC 2822 remains UTC. 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) → 2024-03-01T12:00:00.000Z
• 1709251200000 (milliseconds) → same date
• 2024-03-01 12:00:00 → Unix timestamp + all formats

Limitations & known constraints

• Display timezone — You can display outputs in Local, UTC, or selected IANA zones; RFC 2822 remains in UTC.
• 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.