Unix Timestamp Converter

What Is a Unix Timestamp?

A Unix timestamp is the number of seconds that have elapsed since the Unix epoch: 00:00:00 UTC on Thursday, 1 January 1970. It is the universal, timezone-independent way computers represent points in time. Every major programming language, database, and operating system uses Unix timestamps internally. The same timestamp represents the same absolute moment regardless of timezone — conversion to local time happens only for display.

Seconds vs Milliseconds

Unix timestamps traditionally count seconds, but JavaScript and many modern APIs use milliseconds (multiply by 1,000). A current timestamp in seconds is approximately 10 digits (e.g., 1750000000). A millisecond timestamp is 13 digits (e.g., 1750000000000). If a timestamp-to-date conversion gives you a date in 1970, it almost certainly means you are treating a millisecond timestamp as seconds. This tool accepts both formats automatically.

Why Timestamps Are Used in Development

• Sorting: Timestamps are plain integers — chronological sorting is trivial.
• Arithmetic: Calculate time differences by simple subtraction. Days between two dates: (ts2 - ts1) / 86400.
• Scheduling: Store expiry times as now + duration_in_seconds.
• Logging: Server logs use timestamps for precise, timezone-independent event ordering.
• Cache busting: Append a timestamp to asset URLs to force fresh downloads after updates.

The Year 2038 Problem

Systems storing timestamps as 32-bit signed integers will overflow on 19 January 2038. After that point, a 32-bit counter rolls back to a negative number representing 1901. All modern systems use 64-bit timestamps, which will not overflow for billions of years. If you work with embedded or legacy systems, verify they use 64-bit time storage.