About

This tool provides a bidirectional bridge between machine-readable Unix timestamps and human-readable ISO-8601 date strings. In distributed systems like Solr, Elasticsearch, or Java applications, time is often stored as the number of milliseconds elapsed since the Unix Epoch (January 1, 1970). Debugging these raw numbers requires precise conversion to standard formats.

Unlike simple converters, this tool automatically detects the precision of your input - distinguishing between seconds (10 digits) and milliseconds (13 digits) - and handles Timezone offsets (UTC vs Local) to prevent off-by-one-hour errors common in data migration tasks.

Formulas

The core conversion logic relies on the offset from the Epoch. For a timestamp T in milliseconds:

D=Date(T_ms)

If the input is in seconds (common in PHP/Python), it must be normalized first:

T_ms =

{

T_in × 1000 if length ≤ 10T_in otherwise

The ISO-8601 format follows the standard syntax YYYY-MM-DDTHH:mm:ss.sssZ.

Reference Data

Description	Timestamp (ms)	ISO-8601 Date (UTC)
Unix Epoch	0	1970-01-01T00:00:00.000Z
Billions Second	1000000000000	2001-09-09T01:46:40.000Z
Solr Example (Prompt)	1403784614000	2014-06-26T12:10:14.000Z
Year 2038 Problem	2147483647000	2038-01-19T03:14:07.000Z
Far Future	32503680000000	3000-01-01T00:00:00.000Z

Frequently Asked Questions

A 10-digit timestamp represents seconds since the Epoch (used by PHP, Python, Unix). A 13-digit timestamp represents milliseconds (used by JavaScript, Java, Solr). This tool automatically detects the difference and converts seconds to milliseconds by multiplying by 1000.

The Z stands for "Zulu time" or Zero offset, which indicates that the time is in UTC (Coordinated Universal Time). If the Z is missing, the time might be interpreted as local time, which can lead to errors.

Yes. Dates before Jan 1, 1970, are represented by negative integers. For example, -1000 is one second before the Epoch (Dec 31, 1969, 23:59:59 UTC).

Microsecond timestamps (16 digits) are common in databases like PostgreSQL. This tool will detect the excessive length and truncate the extra precision to fit the standard JavaScript 13-digit millisecond format.