About Us

DateTimeTools is a small set of everyday date and time calculators in one place: a live clock, a Unix timestamp converter, an age calculator, a date difference calculator and a time zone converter. Each one is a tab on a single page, and each one does one job.

Why these tools

The questions this site answers are small and constant. What time is it there? How many days until the deadline? What date does this log timestamp mean? How old is this person exactly, in years and months and days? Individually none of them is difficult, but they arrive one at a time and each one normally costs a search, a click through a cluttered page, and sometimes a cookie banner.

None of these jobs needs a server. They need arithmetic — calendar arithmetic, time zone rules, and a clock — and a browser already has all three. So the decision was made at the start: the page does the work, and your input stays on your device. Everything else follows from that.

How they work

Each tab is hand-written HTML, CSS and JavaScript with no framework and no third-party scripts. The clock reads your device’s system time. The calendar calculations use the browser’s own date handling, extended where the built-in behaviour would be surprising — the age calculator, for instance, counts years and months the way a registry office does rather than the way a naive division would.

Time zone conversion is the one place where a table is unavoidable. Offsets change when governments change them, so no formula can produce them. Instead of shipping our own table, the converter asks your browser for a conversion using its built-in copy of the IANA time zone database. That copy is updated with your browser, which means the answers here stay current without this page having to track every rule change in the world.

A note on accuracy

Everything here is as accurate as your device is. If your system clock is wrong, the live time will be wrong by the same amount. If your browser’s time zone data is old, a conversion near a rule change may be an hour out. For dates before the Gregorian calendar was introduced, the page uses the proleptic Gregorian calendar — the modern calendar extended backwards — which is the convention software follows but may not be the calendar a historical document used.

Leap seconds are ignored, as they are by almost all software, so a Unix timestamp here is the standard one rather than a count of physically elapsed seconds.

How the site is funded

The site is supported by advertising. There is no paid tier, no account and no feature held back behind one. Adverts are kept outside the working area of the tools so they never sit between you and a button you came for.

What these tools are not

They are calculators, not advice. An age calculator can tell you exactly how old someone is; it cannot tell you which date a particular form will accept. A time zone converter can tell you what a moment becomes elsewhere; it cannot tell you whether the meeting is a good idea. Where a limit exists — the accuracy of historical time zone data, the treatment of 29 February, the ignoring of leap seconds — the page says so rather than quietly rounding.

Getting in touch

Corrections, bug reports and requests for tools that do not exist yet are all welcome — see the contact page. Reports of a wrong conversion are especially useful, so please include the date, the two zones and what you expected.

Need Help? Contact us