When to use this
Convert when reading logs, debugging JWT exp claims, checking database rows — anywhere a raw number needs to become a moment.
This page is a focused view of theUnix Timestamp Converter, which has the full set of options.
Unix timestamp to ISO date
A 10-digit Unix timestamp is seconds (10 digits covers every date from 2001-09-09 to 2286-11-20); 13 digits is milliseconds. Paste either below — 1725105600 becomes 2024-08-31T12:00:00.000Z instantly, and the unit is detected from the magnitude, so database timestamps (seconds) and JavaScript timestamps (milliseconds) both convert correctly.
The detection rule is precise: values below 10¹² are treated as seconds, larger ones as milliseconds — a boundary that classifies every timestamp between 1970 and the year 33658 correctly, because 10¹² seconds is 33,658 AD while 10¹² milliseconds is only 2001. The two misconversion signatures are equally exact: a seconds value fed to a milliseconds API lands in January 1970; the reverse lands near the year 56637.
- Unix seconds
- 1788173482
- ISO 8601 (UTC)
- 2026-08-31T10:51:22.000Z
When it goes wrong
“That timestamp is out of range.” means the number overflowed JavaScript's date range (±8.64×10¹⁵ ms from the epoch) — usually a nanosecond timestamp (19 digits): divide by a billion for seconds. A result of 1970-01-something from a legitimate-looking number means you pasted seconds somewhere expecting milliseconds downstream — the converter shows both units so you can hand over the right one.
Next steps
Frequently asked questions
How do I know if a timestamp is seconds or milliseconds?
Length: current dates are 10 digits in seconds and 13 in milliseconds. This tool treats values below 10¹² as seconds and larger values as milliseconds, which matches every date between 1970 and 33658.
Why does the result end in Z?
Z marks UTC in ISO 8601. Unix timestamps are timezone-less by definition — they count seconds since 1970-01-01T00:00:00 UTC — so UTC is the faithful representation.
Do Unix timestamps count leap seconds?
No. Unix time pretends every day has exactly 86,400 seconds; leap seconds are absorbed. For everyday conversion this never matters.