Unix Timestamp Converter

A Unix timestamp (also called epoch time or POSIX time) is the number of seconds that have elapsed since 00:00:00 UTC on January 1, 1970 — the “Unix epoch”. Timestamp 0 is exactly 1970-01-01T00:00:00Z, and 1,000,000,000 was reached on September 9, 2001. Because it is a single number with no timezone attached, the same timestamp represents the same instant everywhere in the world.

Different systems store the count at different precisions, and you can usually tell them apart by digit count: 10 digits are seconds (Python time.time(), most APIs), 13 digits are milliseconds (JavaScript Date.now(), Java), 16 digits are microseconds, and 19 digits are nanoseconds (Go, some databases). This converter detects the unit automatically from the magnitude of the number.

For example, the timestamp 1724400000 (seconds) equals 2024-08-23T08:00:00Z, while 1724400000000 is the same instant expressed in milliseconds. Feeding a seconds value into an API that expects milliseconds produces a date in January 1970 — one of the most common timestamp bugs.