Epoch Time Converter

Introduction:

Epoch time—also called Unix time—counts the whole seconds that have elapsed since 00:00:00 Coordinated Universal Time (UTC) on 1 January 1970. Because it represents moments as a single integer, it is widely used in logging, cryptographic signatures, distributed systems, and databases where a compact, timezone-neutral timestamp simplifies comparison and ordering.

The converter lets you enter either an epoch value or a civil date–time, choose seconds or milliseconds, and pick any time-zone. A reactive engine recalculates the parallel representation instantly, showing ISO 8601, RFC 2822, Julian Day and other formats while keeping the fields synchronised for copy-to-clipboard or CSV export.

Developers auditing log files, analysts aligning events across global services, or students learning date arithmetic can quickly translate a timestamp without installing CLIs or libraries. Always double-check whether the source uses seconds or milliseconds when pasting large integers in systems to avoid misplacing events by a factor of one thousand.

Technical Details:

Unix time encodes a moment as the count of elapsed seconds since the “epoch” of 1 January 1970 00:00:00 UTC. Converting between this scalar and a structured calendar date requires knowing whether the raw value is given in seconds or milliseconds and which time-zone context the human-readable form should reference. Because leap seconds are ignored, Unix time increases monotonically, making it ideal for ordering events but unsuitable for legally critical timestamps that demand absolute civil accuracy.

Core Equation:

t_s – epoch timestamp in seconds; t_ms – epoch timestamp in milliseconds.

Variables & Parameters:

• epoch value – integer seconds or milliseconds.
• epoch unit – choose sec or ms.
• datetime value – calendar input “YYYY-MM-DD THH:MM”.
• tz selection – local, UTC, offset, or named zone.
• tz offset – custom offset ±HH:MM when required.

Assumptions & Limitations:

• Assumes Gregorian calendar for all years.
• Ignores leap seconds.
• Offsets resolve using current IANA definitions.
• Values outside ±285 616 years overflow 64-bit float.

Edge Cases & Error Sources:

• Near-epoch negatives require explicit sign.
• Mis-selecting unit multiplies error by 1000.
• Historic zone shifts may be mis-mapped by browsers.
• Client clock drift skews “live” timestamp preview.

Based on POSIX 1003 “Seconds Since the Epoch”, ISO 8601:2019 date-time standards, and astronomical Julian Day conventions.

No data leaves the browser; the conversion runs entirely client-side.

Step-by-Step Guide:

Follow these actions to translate between an epoch value and a formatted date:

1. Enter an epoch value or pick a calendar date-time.
2. Select the appropriate unit—seconds or milliseconds.
3. Choose time-zone; expand the list for IANA zones or supply a custom offset.
4. Review the instantly refreshed table, parts, or multi-zone tabs.
5. Copy single values, the whole CSV, or download files for audit logs.

If the wrong unit is chosen, results will be incorrect by a factor of 1000.

FAQ:

Glossary:

Epoch

Reference start of Unix time, 1970-01-01 00:00 UTC.

ISO 8601

International date-time string standard.

RFC 2822

Format used by Internet email headers.

Julian Day

Sequential day count beginning 4713 BC.

Time-zone

Region-specific offset from UTC.