What is a Unix Timestamp?
A Unix timestamp is a way of representing a moment in time as a single number — specifically, the number of seconds (or milliseconds) that have elapsed since January 1, 1970, at midnight UTC. This reference point is called the Unix epoch.
Computers and APIs frequently use Unix timestamps because they’re simple, compact, and timezone-independent. A timestamp is just a number, which makes it easy to store, sort, and compare. But for humans, a number like 1713484800 is meaningless without converting it to a readable date and time.
What Does This Tool Do?
This tool converts Unix timestamps to human-readable dates and times, and converts dates back to Unix timestamps — in both seconds and milliseconds. It shows the result in your local timezone as well as UTC.
How to Use This Tool
- Timestamp to date: Paste a Unix timestamp (seconds or milliseconds) into the input — the corresponding date and time is shown instantly.
- Date to timestamp: Enter a date and time to get the corresponding Unix timestamp.
- The current timestamp is shown by default when you open the tool.
Common Use Cases
- Debugging APIs: API responses often include timestamps as numbers — convert them to understand what time they represent.
- Log analysis: Server logs use Unix timestamps; convert them to read the actual dates.
- Scheduling: Calculate timestamps for future dates when working with scheduled tasks or cron jobs.
- Data inspection: Databases often store dates as timestamps — quickly decode them.
Timestamp Reference Points
| Timestamp (seconds) | Date (UTC) | Significance |
|---|---|---|
0 | 1970-01-01 00:00:00 | The Unix epoch |
1000000000 | 2001-09-09 01:46:40 | 1 billion seconds |
1500000000 | 2017-07-14 02:40:00 | |
1700000000 | 2023-11-14 22:13:20 | |
2000000000 | 2033-05-18 03:33:20 | 2 billion seconds |
2147483647 | 2038-01-19 03:14:07 | 32-bit signed integer limit — the “Year 2038 problem” |
A useful mental anchor: timestamps starting with 17 are from late 2023 through 2026; each +31,536,000 is one year.
Seconds, Milliseconds, Micro, Nano
Different platforms use different precisions, and mixing them up is the most common timestamp bug:
| Digits | Unit | Used by |
|---|---|---|
| 10 | seconds | Unix/Linux, most APIs, JWT claims |
| 13 | milliseconds | JavaScript Date.now(), Java |
| 16 | microseconds | Python time.time() scaled, some databases |
| 19 | nanoseconds | Go UnixNano(), high-resolution logging |
If a converted date shows the year 56746, you probably fed milliseconds where seconds were expected; if it shows January 1970 just after midnight, the reverse.
What About the Year 2038 Problem?
Systems that store timestamps as 32-bit signed integers can only count up to 2147483647 — 03:14:07 UTC on January 19, 2038. One second later, the value overflows to a negative number, which naive code interprets as December 1901. Modern 64-bit systems are unaffected (they’re good for about 292 billion years), but embedded devices and legacy databases still need auditing.
Frequently Asked Questions
What's the difference between seconds and milliseconds timestamps?
Standard Unix timestamps count seconds since the epoch. Many modern systems (especially JavaScript) use milliseconds. A 10-digit number is usually in seconds; a 13-digit number is usually in milliseconds.
Does this tool account for timezones?
Yes. Results are shown in both UTC and your device’s local timezone.
Is my data private?
All conversions happen locally in your browser. Nothing is sent to a server.
Do Unix timestamps include leap seconds?
No — Unix time pretends leap seconds don’t exist. Every day is exactly 86,400 seconds. When a leap second occurs, Unix clocks typically repeat or smear a second. For virtually all application purposes you can ignore this; it only matters in scientific and astronomical timing.
Why do two systems show different dates for the same timestamp?
The timestamp itself is timezone-independent — it always refers to the same instant. What differs is the timezone used to display it. A timestamp rendered in UTC and in São Paulo time (UTC−3) will show different wall-clock values for the same moment. That’s why this tool shows both UTC and your local time.