Unix Timestamp Converter (Epoch ↔ Date)
Convert between Unix epoch seconds/milliseconds and human-readable UTC or local dates.
What this calculates
The Unix epoch — January 1, 1970 UTC — is the universal reference point for timestamps in databases, logs, and APIs. This calculator converts between epoch seconds, epoch milliseconds, and human-readable dates in both UTC and your local timezone.
Formula & how it works
Date = new Date(seconds × 1000) or new Date(milliseconds). Epoch = Math.floor(Date.getTime() / 1000) for seconds.
Worked example
Epoch 1747353600 = 2025-05-16 00:00:00 UTC. Same moment in ms: 1747353600000.
Frequently asked questions
Seconds or milliseconds?
Unix originally meant seconds. JavaScript's Date.getTime() returns milliseconds. APIs differ — check the docs.
Year 2038 problem?
32-bit signed epoch seconds overflow on Jan 19, 2038. Modern systems use 64-bit and are unaffected.
Timezones?
Epoch is absolute UTC. Local-time display depends on your machine — same epoch shows different wall-clock times in different zones.