Unix Timestamp: What Those 10 Digits Mean
Seeing numbers like 1700000000 and wondering what date that is? Here's how Unix timestamps work and a free converter.
A Unix timestamp (also called Epoch time or POSIX time) is the number of seconds that have elapsed since January 1, 1970 at 00:00:00 UTC. It is the standard way computers represent time.
Why Unix Timestamp?
- Universal: Same value everywhere in the world (no timezone ambiguity)
- Simple: A single integer, easy to store and compare
- Compact: Only 4 bytes (32-bit) or 8 bytes (64-bit)
- Sortable: Chronological order = numerical order
Seconds vs Milliseconds
Some systems use milliseconds instead of seconds:
| Format | Current (approx) | Example |
|---|---|---|
| Seconds (10 digits) | 1,714,xxx,xxx | 1714567890 |
| Milliseconds (13 digits) | 1,714,xxx,xxx,000 | 1714567890000 |
JavaScript uses milliseconds, while Python and most databases use seconds. Always check which format your data uses.
Common Epoch Dates
| Date | Unix Timestamp |
|---|---|
| Jan 1, 1970 | 0 |
| Jan 1, 2000 | 946,684,800 |
| Jan 1, 2020 | 1,577,836,800 |
| Jan 1, 2025 | 1,735,689,600 |
| Jan 1, 2030 | 1,893,456,000 |
| Jan 19, 2038 | 2,147,483,647 (32-bit max) |
The Year 2038 Problem
32-bit signed integers can store timestamps up to 2,147,483,647 (January 19, 2038). After this date, 32-bit systems will overflow, potentially causing crashes. Most modern systems use 64-bit timestamps, which will not overflow for billions of years.
How to Convert
Use our free Unix timestamp converter to:
- Convert timestamps to human-readable dates
- Convert dates to timestamps
- Get the current timestamp instantly
- Supports both seconds and milliseconds
## Common Timestamp Formats
Different systems use different timestamp formats. Here are the most common ones:
- Unix timestamp (seconds): A 10-digit number like
1700000000. Used by most Unix systems and APIs. - Unix timestamp (milliseconds): A 13-digit number like
1700000000000. Used by JavaScript (Date.now()), Java, and some databases. - ISO 8601:
2023-11-14T22:13:20Z. The international standard. TheZsuffix means UTC. - RFC 2822:
Tue, 14 Nov 2023 22:13:20 +0000. Used in email headers. - RFC 3339: A subset of ISO 8601 used in APIs and protocols.
Why Unix Timestamps Exist
Unix timestamps count seconds since January 1, 1970, 00:00:00 UTC (the "epoch"). This design has practical advantages:
- No timezones: A timestamp represents a single moment in time, unambiguous worldwide
- Easy arithmetic: Subtract two timestamps to get the difference in seconds
- Compact: A 10-digit integer is smaller than a date string
- Sortable: Numerical sort equals chronological sort
The downside: humans cannot read timestamps without conversion. That is why timestamp converters are essential.
The Year 2038 Problem
Traditional 32-bit Unix timestamps overflow on January 19, 2038, because the maximum value of a signed 32-bit integer (2147483647) corresponds to that date. After that, the timestamp wraps to a negative number, causing dates to appear as 1901.
Most modern systems have already migrated to 64-bit timestamps, which will not overflow for 292 billion years. But embedded systems, legacy databases, and some file formats still use 32-bit timestamps and will need updates before 2038.