Privacy

The arithmetic runs on your device

Every calculator on this site runs entirely in your browser. The salary, the loan amount, the property price and every other figure you enter are used to work out an answer on your own device, and working it out sends them nowhere.

There is no account, no sign-in and no form on this site that submits anything, and no server takes part in the arithmetic. The site is a set of pre-built pages, and what your browser asks its host for is what any page is made of: the pages themselves, their scripts and fonts, and the search index, a static file of page names.

What is kept on your device

Two things may be stored in your browser's local storage, and nowhere else. They never leave the device, and this site cannot read them from anywhere but the browser you are using.

The first records your answer to the notice at the bottom of the screen: whether you allowed cookies for measurement. The second holds your basic wage, your allowances and the date you saved them, and only if you chose to save them, so that another calculator can offer them back instead of asking twice.

The button at the foot of every page removes a saved salary whenever there is one, and clearing this site's data in your browser removes both.

Your address bar carries your figures

The inputs you type are written into the page address as you go, after a # sign, so that a calculation can be bookmarked, reloaded or sent to someone else. This is deliberate and it is what makes a result shareable.

The part of any address after a # stays in your browser: it is not sent to Vercel, the company that hosts this site, when the page is requested, and it is not passed on as the address you came from when you follow a link. The figures are still part of the address, though, so they appear in your browser history, and anyone you send the link to can see them. If you would not want a number seen, do not share the link that contains it.

Links made before 24 September 2026 carried the figures after a question mark instead, and what follows a question mark is sent with the request. When one of those links is opened, the browser sends it to Vercel once as it is, and the page then moves the figures behind the # before anything else on it runs.

Measurement

This site uses Google Analytics to count visits and to see which calculators are used. Its code sends Google three things: a page view when a page opens, another each time you move to a different page within the site, and an event named calculate when you press a Calculate button. Each carries the page address without the part that holds your figures, so none of them carries a figure you typed. A test fails if this code starts reading that part of the address.

Google's tag adds details of its own to each of them: the page's title; the address of the page you came from, as your browser reports it; an approximate location worked out from your network address; general details about your browser and device, such as its language, screen size and operating system; and an identifier, kept in a cookie Google's script sets on this site, that lets it recognise the same browser when it comes back.

What the tag goes on to record by itself is decided by settings in the Analytics account, which are changed in Google's dashboard and not in this site's code, so this page says what those settings can record rather than promising which of them are on. They can record that you scrolled to near the end of a page; that you followed a link to another website, with that link's address; that you opened a link to a file; that you started or submitted a form; that you watched an embedded video; and the search terms in the address of a search results page. None of these records what you type into a calculator's fields.

Another of those settings records a page view each time the address in your browser changes without a new page loading. The address it sends leaves out everything after the # sign, which is where this site keeps your figures, so those page views carry no figure you typed either; all they add is a second count of a move this site's own code already counts. This was checked on 24 September 2026 against the tag Google serves for this site: moving to another calculator, going back with the back button and reloading sent no figure.

The account can also be set to look for email addresses, phone numbers and postal addresses that a visitor provides on a page, and to send them to Google after passing them through a one-way hash. No field on this site asks for any of them.

Google sets its own cookies to do this. Blocking cookies, or using a browser or an extension that blocks analytics, does not affect any calculator on this site.

• How Google uses information from sites that use its services
• The browser add-on that stops Google Analytics

Google signals

Google signals is another setting in the Analytics account, switched on and off in Google's dashboard rather than in this site's code. While it is on, Google associates visits to this site with the Google accounts of visitors who are signed in and have turned on ads personalisation, and uses that to add demographic and interest data to the reports and to show how the same people use the site from more than one browser and device.

Whoever runs the account sees only totals: Google says these reports hold only aggregated data and never expose any individual user's. If you do not want your visits associated this way, turn off ads personalisation in your Google account, browse while signed out, or install the browser add-on that stops Google Analytics.

• The ad settings in your Google account

Advertising

Google AdSense is built into this site but is not switched on. No advertising script loads at the moment and no advertising cookies are set by these pages.

If advertising is enabled later, Google and its partners may set cookies and use them to select and measure ads, and this page will be updated to say so on the day it happens rather than afterwards.

The notice at the bottom of the screen

That notice asks whether Google Analytics may use cookies to count your visits. Your answer is kept on your device, and you can change it at any time by clearing this site's data in your browser, which brings the notice back.

If you decline, Google's tag stays on the page but is told not to store or read cookies, so no identifier is kept for your browser, and what it still sends are cookieless signals Google uses to estimate totals. In the European Economic Area, the United Kingdom and Switzerland nothing is stored until you allow it. Elsewhere, until you choose, measurement runs as it does for anyone who allows it.

Changes

The date under the title is the last day this page was compared with the site's code and with what Google's tag actually sends. The intention is that the page is updated, and that date moves with it, whenever something described here changes.

Questions about your data

Write to the address below and it reaches the person who maintains this site. It is the route for anything on this page: what is stored, what you want removed, or a correction to something stated here.