Last updated 18 August 2026.
What you type into a calculator never leaves your device
Every calculator on this site runs entirely in your browser. There is no server-side calculation, no API call, and no logging of inputs, because there is nothing to log to — the site is static files. Your dates of birth, your deadlines and your shift times are yours; we never see them.
One thing to know: when you change an input, the page updates the address bar so the result can be shared by copying the URL. That is a convenience, and it means the values are visible in your own browser history and in any link you paste somewhere. Nothing sends that URL to us.
What we do collect
Standard web-server request logs held by our host, containing IP address, user agent, referring page and the URL requested. They are used to keep the site up and to see which pages are used. If analytics is enabled it is configured not to set advertising identifiers.
Advertising
This site is funded by display advertising. Advertising partners may set cookies or read device identifiers to measure and, where you have consented, personalise the ads you see. That is their processing, under their own policies, not ours — we do not receive that data and we do not sell it.
Google, as one of these partners, uses cookies to serve ads based on your prior visits to this site and to other sites. You can opt out of personalised Google advertising at Google's ad settings, and manage third-party cookie use for personalised advertising across many networks at aboutads.info/choices or, in Europe, youronlinechoices.eu.
Where the law requires a consent choice — the EEA, the UK and Switzerland under the GDPR, and US state privacy laws — that choice is presented before any advertising cookie is set, and it is honoured. Until a certified consent management platform is in place, visitors in the EEA, the UK and Switzerland are served no advertising at all rather than advertising on a consent record that would not meet the standard; that is a deliberate choice and it costs us money rather than you. Declining, or blocking third-party cookies outright, changes nothing about the calculators — none of them depend on a cookie, and the answer is already in the page before any script runs.
When the ad slots are empty, as they are before this site is approved by an advertising network, no third-party code is loaded and no third-party request is made from these pages at all.
Cookies this site sets itself
One, and it is not strictly a cookie: your light or dark theme choice is kept in your browser's local storage so the page does not flash the wrong colour on the next visit. It never leaves your device and it identifies nothing.
Children
This site is a general-audience utility and is not directed at children under 13. We do not knowingly collect personal information from them.
Your choices
You can browse with cookies blocked, with JavaScript disabled — the answer is already in the page before any script runs — and with an ad blocker. All of that is fine. If you want to ask what is held about you, the contact page is the route.
Changes
This policy may change; the date at the top says when it last did.