Cookie Policy

A cookie is a small text file that a website asks your browser to store on your device. The next time you visit, the site can read that file back.

Cookies exist because the web is otherwise forgetful. Without them, a site has no way of knowing that the person loading page three is the same person who loaded page two a moment earlier. Cookies are how a shopping basket stays filled, how a login persists, and how a site remembers that you already dismissed a notice.

A cookie is a plain text file. It cannot run programs, install anything, or read other files on your device.

Two useful distinctions

Session versus persistent. A session cookie is deleted when you close your browser. A persistent cookie stays until it expires or you remove it.

First-party versus third-party. A first-party cookie is set by the website you are visiting. A third-party cookie is set by a different company whose content appears on that page — an analytics script or an advertisement, for example.

Similar technologies

Several other techniques do broadly similar work, and this policy covers them too:

• Local storage — a larger store your browser keeps for a site, which persists until cleared.
• Pixels or web beacons — tiny invisible images that register when a page or email was opened.
• Device or browser signals — technical details such as screen size and browser version that a service can read automatically.

This website may use cookies for three purposes, described in detail in the sections that follow.

Essential cookies are those needed for the website to function properly and for basic preferences to be remembered. They are set by this website rather than by an outside company.

They may be used to:

• Remember that you have dismissed a notice or banner, so it does not reappear on every page.
• Record a cookie consent choice, where a consent tool is in use.
• Support core content management functions provided by the website platform.
• Help protect against spam and automated abuse of the contact form.

These cookies do not track you across other websites and are not used for advertising. Because they are necessary for the site to behave as expected, they are generally not subject to consent — but you can still block them through your browser if you wish, accepting that some things may not work smoothly.

Analytics cookies help us understand how the website is used overall — how many people visit, which pages are read most, what devices are common, and where visitors run into trouble. That information tells us what to fix and what to write next.

Where analytics is active on this website, it is provided by Google Analytics, a service operated by Google LLC. That service may collect:

• Pages viewed and the order in which they were viewed
• Time spent on the site
• Approximate location derived from your IP address, usually to city level
• Device type, screen size, browser and operating system
• The page or search that referred you here

Analytics data is used in aggregate. We do not use it to identify individual visitors, and it does not contain anything you typed into the calculator, because those values are never transmitted anywhere.

Details of what Google collects and how long it retains it are set out in the Google Privacy Policy. Google also offers a browser opt-out add-on that works across every website using Google Analytics.

Advertising is what allows this calculator to remain free to use. Where advertisements are displayed, they may be served through Google AdSense, a service operated by Google LLC, which may set its own cookies.

Advertising cookies are typically used to:

• Decide which advertisement to show on a page.
• Limit how many times you see the same advertisement.
• Measure whether an advertisement was seen or clicked.
• Personalise advertising based on your browsing, where that setting is enabled.
• Detect fraudulent clicks and invalid traffic.

We do not share your calculator inputs with any advertiser or ad network, because we do not have them. Nothing you enter into the tool reaches an advertising system through us.

You can review how Google uses information in advertising through Google’s advertising policies, and you can turn off personalised advertising through Google My Ad Center.

Advertising cookies are set and controlled by the advertising provider, not by us. We do not have access to the data they collect, and we cannot delete their cookies on your behalf. Section 7 explains how you can limit or block them.

Some cookies on this website are placed by other companies rather than by us. Analytics and advertising cookies both fall into this category.

It is worth being clear about what this means in practice. When a third-party script runs on a page, that company sets and reads its own cookies directly. We do not see them, cannot modify them, and cannot remove them for you. Their use of that information is governed by their own privacy policies, not by ours.

Because these cookies belong to companies whose content may appear on many websites, they can in principle be used to recognise a browser across different sites. That is how cross-site advertising personalisation works, and it is one of the main reasons people choose to block third-party cookies.

We encourage you to read the privacy documentation of any service named on this page if you want to understand exactly what it collects.

You are in control here, and you have several ways to exercise that control.

Through your browser

Every major browser lets you view existing cookies, delete them, block them selectively, or block them entirely. Cookie settings are usually found under privacy or security options:

Menu names vary between versions, so if you cannot find the option, searching your browser’s help for “cookies” will get you there. Private or incognito browsing also discards cookies when the window is closed.

Through consent controls

Where a cookie consent tool is in use on this website, you can accept or decline non-essential cookies when you first visit, and you can change that choice later through the consent control provided on the site.

Through provider opt-outs

Analytics and advertising companies generally offer their own opt-out mechanisms, which work across every website using that service rather than only this one. These are usually documented on the provider’s own website.

What blocking cookies means for this site

• The calculator is unaffected. It sets no cookies and needs none. Block everything and it works identically.
• Analytics simply stops counting your visit. Nothing on the page changes.
• Advertising may still appear, but it will be less relevant to you. Blocking advertising cookies limits personalisation; it does not remove advertisements.
• Some conveniences may reset, such as a dismissed notice reappearing on each visit.

This policy may be updated from time to time — for example if we add or change a service, if a provider changes how it operates, or if wording needs clarifying.

When that happens, the revised policy is posted on this page and the “Last Updated” date at the top is changed. Where a change materially affects what is collected, we will make a reasonable effort to make it noticeable rather than quietly amending the text.

Continued use of the website after an update means you accept the revised policy. This page is worth a glance occasionally if the subject matters to you.

This policy should be read alongside our Privacy Policy, which covers how information is handled more broadly.