Timestamp Converter
Free online Unix timestamp converter. Convert epoch seconds/milliseconds to human dates and back, in any timezone — instant and accurate.
Timestamp Converter guide
What Unix time actually counts
A Unix timestamp is the number of seconds elapsed since 1970-01-01 00:00:00 UTC — the “epoch”. Because it is a single plain integer, it sorts correctly as text, survives timezone differences untouched, and never needs a calendar library to store. That is why every backend database, log file and API you will ever touch uses it for machine time.
JavaScript raised the stakes: its Date.now() returns milliseconds, so 13-digit timestamps are everywhere in web code. A 10-digit value is seconds, 13 digits is milliseconds — mixing them up produces dates 1,000 years off, the classic symptom being “my data shows January 1970”.
Timezones: the part that bites
The timestamp itself has no timezone — 1700000000 means the same instant in Tokyo and New York. Timezone enters only at display time. When debugging “off by 8 hours” bugs (a classic for UTC+8 users), the question is always: which layer converted it wrongly — the database storing local time as if it were UTC, the API serializing with a shifted timezone, or the client rendering in the wrong zone?
- Store and transmit UTC (or raw timestamps) everywhere.
- Convert to local time only at the final rendering step.
- Never mix “timestamp without timezone” database columns with local-time input.
Practical reference points
A few anchors help sanity-check values at a glance: 0 = 1970-01-01, 1000000000 = 2001-09-09, 2000000000 = 2033-05-18. Current-era timestamps begin with 17 (2023-2028) then 18 — if a “current” timestamp starts with anything else, something is wrong.