Mastering Unix Epoch Timestamps, Timezones, and ISO 8601

Unix Epoch time measures the number of seconds elapsed since 00:00:00 UTC on January 1, 1970. It is the universal language of database logs, JWT tokens, and distributed systems.

Convert timestamps and timezones seamlessly:

• Convert between epoch seconds/millis and human dates with the Timestamp Converter
• Compare time differences across world cities with the Time Zone Converter

Seconds vs Milliseconds

• Seconds (10 digits): 1755291600 (Standard in Unix, Python, PHP, JWTs).
• Milliseconds (13 digits): 1755291600000 (Standard in JavaScript Date.now(), Java).

// Current time conversions in JavaScript
const nowMs = Date.now(); // 13 digits
const nowSec = Math.floor(Date.now() / 1000); // 10 digits
const isoString = new Date(nowMs).toISOString(); // "2026-08-15T19:00:00.000Z"

Convert timestamps in your browser with the Timestamp Converter.