Dev & Computing · Unix 时间戳（Unix Timestamp） · Updated 2026-10-25
What Is Unix Timestamp?
Definition
A Unix timestamp counts seconds since 1970-01-01 00:00:00 UTC (the epoch) — how most languages and databases store an instant. It carries no time zone of its own: the 10-digit timestamp 1761350400 points to the same moment in Beijing and New York; only the local rendering differs. 32-bit systems counting seconds overflow on 19 Jan 2038 (the Y2038 problem); modern 64-bit systems and millisecond (13-digit) timestamps are unaffected.
Formula
10 digits = seconds; 13 digits = milliseconds; a Beijing date = format (timestamp + 8×3600) as UTC then take the date part
Worked Example
1761350400 is 2025-10-25 00:00:00 UTC = 2025-10-25 08:00 in Beijing = 2025-10-24 20:00 in New York — three different "clock readings", one instant.
Common Misconception
Treating timestamps as "local seconds" and adding a time-zone offset again (the classic double-offset 8-hour bug); mixing 10-digit seconds with 13-digit milliseconds in comparisons breaks ordering — normalize units first.
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