Question 1

What is a Unix timestamp?

Accepted Answer

A Unix timestamp (also called Unix epoch time or POSIX time) is the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970 (the 'Unix epoch'), excluding leap seconds. It is the standard way computers represent absolute time. Most systems store it as a 32-bit signed integer, which will overflow on 19 January 2038 (the 'Y2K38' or 'Year 2038' problem).

Question 2

How does this tool detect seconds vs milliseconds vs microseconds vs nanoseconds?

Accepted Answer

We look at the digit count and magnitude of the input. Roughly: 1-10 digits = seconds, 11-13 digits = milliseconds, 14-16 digits = microseconds, 17+ digits = nanoseconds. You can always override with the unit selector. All conversions are done with BigInt so microsecond and nanosecond precision is never rounded by JavaScript's 53-bit float Number.

Question 3

What happens in 2038?

Accepted Answer

On 19 January 2038 at 03:14:07 UTC, the signed 32-bit Unix timestamp (2,147,483,647) will roll over to a negative number, breaking any system that stores time as a 32-bit signed int. This tool always uses BigInt internally and warns you if your input is near or beyond that boundary so you know which legacy systems would break.

Question 4

Which non-Unix epochs are supported?

Accepted Answer

Windows FILETIME (100-nanosecond intervals since 1601-01-01 UTC), LDAP/NT (100-ns intervals since 1601), NTP (seconds since 1900-01-01 with a 32-bit seconds field that wraps in 2036), Apple/Cocoa (seconds since 2001-01-01 UTC), Excel serial date (days since 1899-12-30, with Excel's 1900 leap-year bug called out), and MongoDB ObjectId embedded timestamps (4-byte seconds since 1970).

Question 5

What extra features does this tool have versus others?

Accepted Answer

(1) Auto unit detection (s/ms/μs/ns) with manual override. (2) BigInt precision so μs/ns never lose digits. (3) Timestamp → date AND date → timestamp both directions. (4) 6 output formats (ISO 8601, RFC 2822, locale, day-of-week, relative time, UTC + local). (5) 8 epoch systems (UNIX, JS ms, FILETIME, LDAP/NT, NTP, Cocoa, Excel serial, Mongo ObjectId). (6) Live ticking current-epoch clock in any unit. (7) Batch mode: paste thousands of timestamps, get a converted table + CSV export. (8) Start/end-of-year/month/day epoch helpers. (9) 2038 (signed 32-bit) overflow warning. (10) Code snippets for getting/converting epoch in 15+ languages. (11) Color-coded unit badge. (12) localStorage history (max 20, metadata only). (13) Shareable URL with ?ts=...&unit=... (fragment-encoded).

Question 6

Is my data sent anywhere?

Accepted Answer

No. All conversions run locally with BigInt and Intl.DateTimeFormat. History is stored in localStorage on this device only and contains metadata (input length, unit, epoch kind), never your raw data.

Unix Timestamp / Epoch Converter

Current Unix epoch

Start / end-of-period helpers (UTC, ms)

Code snippets (17 languages)

How to use

Current Unix epoch

Start / end-of-period helpers (UTC, ms)

Code snippets (17 languages)