Unix Timestamp Converter (Epoch ↔ Date)

What is a Unix timestamp?

A Unix timestamp (epoch time, POSIX time) is the number of seconds elapsed since 1970-01-01 00:00:00 UTC, not counting leap seconds. It describes one instant regardless of time zone, which is why databases, logs, JWT exp claims and APIs use it. Time zones only matter when you turn that instant into a calendar date and clock time for a person.

Seconds, milliseconds, microseconds or nanoseconds?

Different platforms count in different units, and mixing them up is a classic bug (dates in 1970 or in the year 55,000). The converter looks at the number of digits:

Getting the current timestamp in code

// JavaScript
Math.floor(Date.now() / 1000)
# Python
import time; int(time.time())
# Bash
date +%s
-- PostgreSQL
SELECT extract(epoch FROM now());

Time zones and daylight saving

When you convert a date to a timestamp, the wall-clock time is interpreted in the selected IANA zone (for example Europe/Istanbul or America/New_York) using your browser's time zone database. During a spring-forward jump some local times do not exist; during a fall-back the same local time occurs twice and the earlier instant is used. The tool tells you when this happens.

The year 2038 problem

Systems that store seconds in a signed 32-bit integer overflow at 2147483647, which is 2038-01-19 03:14:07 UTC. Modern platforms use 64-bit values, but older embedded systems and database columns may still be affected.