Date & Time

Unix Timestamp Conversion Guide for Product Teams

Learn how Unix timestamps work, when seconds differ from milliseconds, and how to avoid common date conversion mistakes.

May 6, 20264 min read

Unix timestamps represent time as a count from January 1, 1970 UTC. They are compact, sortable, and common in databases and APIs.

Seconds and milliseconds

Many backend systems use seconds while JavaScript uses milliseconds. A 10-digit value is usually seconds. A 13-digit value is usually milliseconds.

Time zones

Timestamps are absolute, but displayed dates depend on time zone. When debugging, compare UTC and local output so everyone is looking at the same moment.

Logs and analytics

Timestamp conversion is especially useful when reviewing logs, scheduled jobs, and analytics exports.

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