What a Unix timestamp actually is
A Unix timestamp (also called 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. It packs a complete, unambiguous moment in time into a single integer: no month names, no date formats, no daylight-saving rules, no timezone field to get wrong.
That is why databases, APIs, log files, and operating systems all lean on it. Integers are compact to store, trivial to sort and compare, and identical on every system in the world. The timestamp 1755216000 means exactly the same instant in Tokyo, Berlin, and São Paulo — only the human-readable rendering differs.
The flip side is that a raw timestamp is unreadable, which is where a converter earns its keep: paste a number out of a log line or a database row and see the moment it refers to, in both your local timezone and UTC.
Converting a timestamp to a date
Paste any epoch value into the Timestamp → Date converter. The tool detects the unit automatically: a 10-digit number is read as seconds and a 13-digit number as milliseconds, which is the difference between a Unix timestamp from a backend system and one produced by JavaScript’s Date.now(). You get the result three ways at once — your local timezone, strict UTC, and ISO 8601 format — so you can paste the right representation into a bug report, a query, or a support ticket.
This is the everyday move when debugging: a server log says an error happened at 1723622400, your monitoring dashboard shows a spike at “14:00 local”, and the converter tells you whether they are the same event or an hour apart.
Converting a date to a timestamp
The reverse direction matters just as often. Pick a date and time in the Date → Timestamp panel and you get the epoch value to embed in an API payload, seed a database record, set a cache expiry, or hard-code a test fixture. Timestamps are the standard currency for JWT expiry claims (exp, iat, nbf), rate-limit windows, and scheduled-job comparisons, all of which expect epoch seconds rather than formatted dates.
Epoch boundaries for range queries
A large share of real-world timestamp work is answering “everything from this day / this month / this year”. The Epoch Calculator gives you the exact second boundaries — start of today, end of the month, start of the year — so a query like created_at BETWEEN start_of_month AND end_of_month uses precise integers instead of hand-derived guesses that silently miss the last hour of the range.
Boundary values are also what you want for partitioning data, bucketing analytics by day, and writing retention policies that delete records older than a cutoff.
Seconds vs milliseconds — and the year 2038
The most common timestamp bug is a unit mismatch. Feed a milliseconds value where seconds are expected and your date lands tens of thousands of years in the future; do the reverse and you are back in January 1970. The 10-vs-13-digit rule of thumb (and this converter’s auto-detection) catches it instantly. Some systems go further — microseconds (16 digits) and nanoseconds (19 digits) appear in high-resolution logging — but seconds and milliseconds cover almost everything in application work.
The “year 2038 problem” is what happens to systems that store Unix time in a signed 32-bit integer: it overflows at 03:14:07 UTC on 19 January 2038. Modern 64-bit systems are unaffected, but the constraint still lives in old embedded devices, file formats, and database column types — worth knowing when you see a suspicious cap on how far ahead a date field will go.
Time unit conversions
The Time Unit Converter answers the supporting questions that come up alongside timestamps: how many seconds in a day (86,400), a week (604,800), or thirty days (2,592,000). These are the numbers you reach for when setting TTLs, cookie lifetimes, cache-control max-age headers, and token expiry windows — and getting them from a converter beats mental arithmetic that is off by a factor of 60.