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Timestamp Converter
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Convert between Unix timestamps (seconds or milliseconds) and ISO 8601 / human-readable dates. Type into either field and the other updates live. Auto-detects ms vs seconds based on length (10 digits = seconds, 13 digits = ms). Shows the current Unix timestamp at the top with a Copy button so you can grab “now” without opening a calculator.
Why this matters: Unix timestamps (seconds since 1970-01-01 00:00:00 UTC, also called epoch time) are the universal language of computer time. Every database, every log, every JSON-API response, every server-side system uses them. But humans don’t read 1717545600 as “June 4, 2024” — you have to convert. This tool removes that friction.
The seconds-vs-milliseconds split confuses everyone: JavaScript Date.now() returns milliseconds (13 digits in 2026); most other languages (Python time.time(), Go, Java SimpleDateFormat, PostgreSQL EXTRACT(epoch)) return seconds (10 digits); some APIs mix them inconsistently (a JSON response with one timestamp in seconds and another in ms is a real thing). The auto-detection in this tool uses length heuristic: 10 digits = seconds, 13 = ms, others ambiguous (treats as seconds for safety).
Nasıl Kullanılır
- See the current Unix timestamp at the top of the tool — updated each second. Click 'Copy to fields below' to use 'now' as your conversion input.
- Type into the Unix field (10 or 13 digits) — the ISO field auto-updates with the human-readable form.
- Or type into the ISO field (any common format: 2024-06-04, 2024-06-04T10:30:00Z, 'June 4 2024 10:30 AM') — the Unix field auto-updates.
- The result shows in your local timezone by default; toggle to UTC for protocol-correct values.
- Copy whichever you need to your destination (database, JSON, log).
Ne Zaman Kullanılır
- Reading log files where times are stored as Unix timestamps.
- Debugging API responses with epoch-time fields.
- Computing time-since values (paste current timestamp + paste old timestamp, subtract, get duration).
- Filling 'as-of' fields in test data with specific timestamps.
- Cross-language work where you have a Unix timestamp from one system and need to read it in another timezone or format.
Ne Zaman Kullanılmaz
- Date arithmetic (add 30 days, subtract 6 months) — use a date-time library or our date-calculator tool.
- Timezone conversion across different timezones — use the time-zone-converter tool.
- Fuzzy human dates ('next Tuesday', '3 weeks ago') — use a natural-language date parser.
- Sub-second precision needs (microseconds, nanoseconds) — this tool is millisecond-precision max.
Yaygın Kullanım Senaryoları
- Quick conversion during a typical workday
- Pre-decision sanity-check on inputs and outputs
- Educational use — demonstrating the underlying concept
- Onboarding a colleague who needs the same calculation/conversion
Sık Sorulan Sorular
How is ms vs seconds detected?
By length. 10 digits = seconds (e.g. 1717545600 = 2024-06-04 16:00:00 UTC). 13 digits = ms (e.g. 1717545600000 = same moment). 11-12 digits = ambiguous (could be either, treated as seconds for safety). The split point isn't perfect for far-future timestamps (year 5000+) but works for any plausible date today.
Why does JavaScript use ms when everyone else uses seconds?
Historical accident. JavaScript's Date object was designed to match Java's java.util.Date (1995), which stored milliseconds. Most other languages picked seconds for simplicity. The mismatch causes bugs whenever data moves between JS and Python / Go / SQL — convert at the boundary by multiplying or dividing by 1000.
What is Unix epoch time?
Seconds (or milliseconds) since 1970-01-01 00:00:00 UTC. The standard reference point for time in computing, named after Unix's invention era. Negative values represent dates before 1970. The choice of 1970 was arbitrary — Unix's developers needed an epoch and 1970 was the year they did the work.
What's Y2K38?
January 19, 2038 03:14:07 UTC — the moment when 32-bit signed Unix timestamps overflow (2^31 − 1 = 2147483647 seconds since 1970). Like Y2K but for older systems still using 32-bit time_t. Most modern systems use 64-bit timestamps (good until year ~292 billion AD), but embedded systems, some database fields, and legacy code may still hit this in 2038. Worth checking if your code handles dates beyond 2038.
How do I include timezone?
ISO 8601 supports two ways: 'Z' for UTC (`2024-06-04T10:30:00Z`), or explicit offset (`2024-06-04T10:30:00-05:00` for EST). The Unix timestamp itself is always UTC by definition (seconds since the epoch in UTC); when you display a Unix timestamp in a timezone, you're applying a local-time projection of the same UTC moment. The tool defaults to your local timezone for the ISO field; toggle to UTC for protocol-safe values.
Why do my timestamps from Excel look like '45000'?
Excel uses serial dates: number of days since 1900-01-01 (with a famous off-by-one due to a bug Excel preserved for backward compat). 45000 ≈ year 2023. To convert Excel serial to Unix: `(serial - 25569) * 86400` for whole days, then add fractional-day for time-of-day. Different system, different epoch, different units — confusing.