What is a Unix Timestamp?
A Unix timestamp is a way of tracking time as a running total of seconds. It counts the number of seconds that have elapsed since the Unix Epoch - January 1st, 1970 at 00:00:00 UTC.
Quick Definition
Unix time (also known as Epoch time, POSIX time, or Unix timestamp) is a system for describing a point in time. It is the number of seconds that have elapsed since 00:00:00 Thursday, 1 January 1970, Coordinated Universal Time (UTC).
How Unix Timestamp Works
Unix Epoch Begins
January 1, 1970, 00:00:00 UTC = Timestamp 0
Counting Seconds
Every second that passes adds 1 to the timestamp
Current Time
Right now = 1768142403 seconds since Unix Epoch
Examples of Unix Timestamps
| Unix Timestamp | Human-Readable Date |
|---|---|
| 0 | January 1, 1970, 00:00:00 UTC |
| 1000000000 | September 9, 2001, 01:46:40 UTC |
| 1609459200 | January 1, 2021, 00:00:00 UTC |
| 1735689600 | January 1, 2025, 00:00:00 UTC |
| 2147483647 | January 19, 2038, 03:14:07 UTC (32-bit limit) |
Why Do We Use Unix Timestamps?
✓ Simple & Universal
Works across all programming languages, databases, and systems worldwide.
✓ Easy to Calculate
Simple arithmetic for time differences - just subtract two timestamps.
✓ No Timezone Issues
Always in UTC, avoiding timezone and daylight saving complications.
✓ Compact Storage
Just a single number - efficient for databases and file systems.
Unix Timestamp in Programming Languages
JavaScript
// Get current Unix timestamp const timestamp = Math.floor(Date.now() / 1000); // Convert Unix timestamp to Date const date = new Date(timestamp * 1000);
Python
import time import datetime # Get current Unix timestamp timestamp = int(time.time()) # Convert Unix timestamp to datetime dt = datetime.datetime.fromtimestamp(timestamp)
PHP
// Get current Unix timestamp
$timestamp = time();
// Convert Unix timestamp to date
$date = date('Y-m-d H:i:s', $timestamp);Common Questions
What happens after January 19, 2038?
This is known as the "Year 2038 problem." On 32-bit systems, Unix time will overflow at 03:14:07 UTC on January 19, 2038. However, modern 64-bit systems can represent dates billions of years into the future.
Can Unix timestamps be negative?
Yes! Negative Unix timestamps represent dates before January 1, 1970. For example, -86400 represents December 31, 1969.
What's the difference between Unix time and Epoch time?
They're the same thing! "Epoch time," "Unix time," "Unix timestamp," and "POSIX time" all refer to the same system of counting seconds since January 1, 1970, 00:00:00 UTC.
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Try our free Unix timestamp converter tools