🕐 Unix Timestamp Converter
Convert between Unix timestamps and human-readable dates.
What Is a Unix Timestamp?
A Unix timestamp (also called Unix epoch time or POSIX time) is the number of seconds that have
elapsed since January 1, 1970, 00:00:00 UTC — known as the "Unix epoch." This single integer
represents a specific moment in time, regardless of time zone, making it the universal time
representation in computing. For example, the timestamp 1700000000 represents
November 14, 2023, at 22:13:20 UTC.
Why Use Unix Timestamps?
- Time Zone Independence: Timestamps are always in UTC, eliminating time zone confusion when storing and comparing dates across systems.
- Simple Arithmetic: Calculate time differences by simply subtracting two integers. No need to handle months, leap years, or daylight saving time.
- Compact Storage: A single 32-bit or 64-bit integer is more efficient than storing formatted date strings.
- Universal Standard: Every programming language, database, and operating system supports Unix timestamps.
- Sortable: Timestamps are naturally sortable as integers — larger values are more recent.
Timestamp Precision
| Precision | Unit | Digits (approx.) | Used By |
|---|---|---|---|
| Seconds | s | 10 digits | Unix/Linux, most APIs, PHP, Python |
| Milliseconds | ms | 13 digits | JavaScript (Date.now()), Java, Elasticsearch |
| Microseconds | µs | 16 digits | PostgreSQL, high-precision logging |
| Nanoseconds | ns | 19 digits | Go, InfluxDB, high-frequency trading |
The Year 2038 Problem
32-bit signed integers can store timestamps up to 2,147,483,647 (January 19, 2038, 03:14:07 UTC).
After this point, 32-bit timestamps overflow — similar to the Y2K problem. Most modern systems use
64-bit timestamps, which can represent dates billions of years into the future.
Common Use Cases
- API Date Fields: Many REST APIs use Unix timestamps for
created_at,updated_at, andexpires_atfields. - JWT Expiration: JWT tokens use Unix timestamps for the
exp(expiration) andiat(issued at) claims. - Database Storage: Store dates as integers for efficient indexing, sorting, and range queries.
- Log Analysis: Convert log timestamps to human-readable dates for debugging and monitoring.
Frequently Asked Questions
What is the difference between Unix time and ISO 8601?
Unix time is an integer (e.g., 1700000000). ISO 8601 is a human-readable string format
(e.g., 2023-11-14T22:13:20Z). Both represent the same moment in time. Use Unix timestamps
for computation and ISO 8601 for display and interchange.