What is a Unix Timestamp?
A single number representing any moment in time, counted from January 1, 1970.
A Unix timestamp (also called Epoch time or POSIX time) is simply the count of seconds since January 1, 1970, 00:00:00 UTC — a date called the "Unix Epoch."
Why 1970? That's roughly when Unix was being developed at Bell Labs, and engineers needed a consistent starting point. The number 0 represents midnight on that historic day.
This elegant approach means any date can be expressed as a single integer — easy to store, compare, and transmit across systems worldwide.
- 0 = January 1, 1970 00:00:00 UTC (The Epoch)
- 1000000000 = September 9, 2001 01:46:40 UTC
- 1704067200 = January 1, 2024 00:00:00 UTC
Try it: Decode a Timestamp
Unix timestamps are timezone-independent — the same number means the same instant everywhere on Earth.
Seconds vs Milliseconds: Know the Difference
10 digits = seconds, 13 digits = milliseconds. One of the most common debugging headaches!
Standard Unix timestamps are in seconds (10 digits for current dates). But JavaScript, Java, and many modern APIs use milliseconds (13 digits).
This 1000× difference causes countless bugs! If you see a date in 1970, you probably passed seconds where milliseconds were expected (or vice versa).
Quick rule: If the number starts with "17" and has 10 digits, it's seconds in the 2024-2025 range. If it has 13 digits, it's milliseconds.
- Seconds: 1704067200 (10 digits)
- Milliseconds: 1704067200000 (13 digits)
- Both = January 1, 2024 00:00:00 UTC
Try it: Seconds or Milliseconds?
Always check your documentation — seconds vs milliseconds is the #1 timestamp debugging issue.
🎉 Fun Epoch Milestones
Developers celebrate cool timestamps like birthdays! Here are the famous ones.
Programmers love cool numbers, and timestamps are no exception. "Epoch parties" have been thrown at data centers and offices worldwide!
The 1 billionth second was September 9, 2001 at 01:46:40 UTC. Some called in sick just to watch the counter flip.
The most celebrated timestamp ever? 1234567890, which occurred on February 13, 2009 at 23:31:30 UTC. The sequential digits made it irresistible!
- 0 — The Big Bang (of Unix), Jan 1, 1970
- 1000000000 — "Billion-second Birthday," Sep 9, 2001
- 1234567890 — "The Sequential," Feb 13, 2009
- 2000000000 — Coming: May 18, 2033 🎈
Try it: Find Your Birthday's Timestamp
Mark your calendar for timestamp 2000000000 — it's the next big epoch party!
The Y2K38 Problem: When 32-bit Time Runs Out
On January 19, 2038, old systems will think it's 1901. Here's why.
Old 32-bit systems store timestamps as a signed 32-bit integer. The maximum value is 2,147,483,647, which equals January 19, 2038 at 03:14:07 UTC.
One second later, the integer overflows and becomes negative — representing December 13, 1901! This is the "Year 2038 Problem" or Y2K38.
Modern 64-bit systems don't have this issue. They can handle dates 292 billion years into the future — long after our sun burns out! 🌞
- 2147483647 — The 32-bit limit (Jan 19, 2038)
- 2147483648 — Overflow! Shows as Dec 13, 1901
- 9223372036854775807 — 64-bit limit (year 292,277,026,596)
Try it: Test the Limits
Check your legacy systems before 2038 — if they're 32-bit, they need updating!
Get Timestamps in Any Language
Copy-paste ready code for JavaScript, Python, PHP, Go, Ruby, and Bash.
Every programming language has built-in ways to get and convert Unix timestamps. Here are the most common patterns.
JavaScript uses milliseconds by default (Date.now()), while Python, PHP, and Bash use seconds. Always check your language's convention!
Pro tip: When debugging, console.log/print the timestamp and paste it into a converter to verify you're getting what you expect.
- JS: Math.floor(Date.now()/1000) for seconds
- Python: import time; int(time.time())
- PHP: time()
- Bash: date +%s
Try it: Verify Your Code
Bookmark a timestamp converter — you'll use it more than you expect.
Best Practices for Timestamps
Store in UTC, display in local time, and always validate your inputs.
Always store timestamps in UTC. Unix timestamps ARE UTC by definition, but when storing formatted dates, be explicit.
When displaying to users, convert to their local timezone. Users don't think in UTC!
Validate timestamp inputs — a 10-digit timestamp that starts with "9" is in the 1980s-2000s range, while "17" is 2020s. If your user enters "2024", they probably meant a year, not a timestamp!
- < 0: Before 1970 (valid but unusual)
- 0-999999999: 1970-2001 (probably seconds)
- 1000000000-1999999999: 2001-2033 (current era in seconds)
- > 1e12: Probably milliseconds
Try it: Convert a Date
When in doubt, convert and display the date to verify — timestamps are easy to mess up!
Frequently Asked Questions
Can Unix timestamps be negative?▼
Why does my timestamp show the wrong date?▼
How do I handle timestamps across time zones?▼
What's the maximum timestamp value?▼
Should I use seconds or milliseconds?▼
Ready to convert timestamps?
Use our full converter with all formats, copy buttons, and live current timestamp display.
Open Unix Timestamp Converter→