Most privacy policies are written to be legally defensible rather than read. This one is written to be read, because the whole argument of this site is that you can check what it does. Where something is genuinely a compromise, it says so rather than burying it.
calc.units in browser local storage
That is the complete list of what this site itself keeps about you. Local storage is not a cookie: it is never attached to a request, so it never travels to any server, ours or anyone else's. It exists so that every calculator opens in the units you picked the first time, instead of asking again on every page.
Your measurements are not stored at all — not in local storage, not anywhere. Reload the page and they are gone. That is deliberate: the numbers you type into a calculator can say a good deal about your house, and there is no version of this site that needs to know them.
This site is funded by display advertising and nothing else. No affiliate links, no lead generation, no commission on anything you buy, no supplier paying for placement. That matters for the reason repeated on every page: a calculator paid for by the people selling you materials can never tell you to buy fewer of them. Ours can, and does.
The cost of that independence is that a third party — Google, through its AdSense programme — serves the ads, and Google collects data in order to do it.
We do not receive any of this. We can see how much the ads earned in aggregate. We cannot see who you are, what you searched, what you calculated or where you went next. The advertising system is deliberately not connected to the calculators, and the calculators send nothing to it.
If you are in the UK, the EEA or Switzerland, you will see a consent prompt before personalised advertising is shown. We would rather not put a banner in front of a calculator, and for most of this site's life there was nothing to consent to. That changed when advertising was switched on, and pretending otherwise would be worse than the banner.
Non-personalised ads still involve a request to Google and still use limited data — such as approximate location and the page you are on — to serve and measure an ad and to limit how often you see the same one. That is Google's description, not a claim of ours.
We use Cloudflare Web Analytics to see which pages people read. It was chosen specifically because it is cookieless and does not fingerprint or track individuals across sites.
The site is static files served by Cloudflare Pages. There is no application server, no database and no user accounts — there is genuinely nothing to log in to and nothing to breach. Like every host on the internet, Cloudflare processes the technical details of a request (IP address, browser, page requested) in order to deliver the page and to block attacks. We do not have access to those logs as an analytics tool and do not use them to build any picture of you. Cloudflare's own privacy policy governs that processing.
There is no contact form anywhere on this site, for the same reason there is no analytics script on it — a form routes what you write through a third party. If you email us, we have your email and whatever you wrote, and we keep it only as long as it takes to deal with. We will not add you to a mailing list, because there isn't one, and we will not pass it to anyone.
Under UK and EU data protection law you have the right to ask what personal data is held about you, to have it corrected or deleted, and to object to its processing.
In our case the answer is short: we hold none. There is no account, no profile and no record of your visit that identifies you. The one thing this site stores sits in your own browser and you can delete it yourself in a few seconds.
For the data Google holds in connection with the advertising, Google is the controller and its own tools are the route: Google's data and privacy controls. We cannot reach into it on your behalf, and any site claiming it can is overstating things.
This site is a set of building-material calculators aimed at adults doing building work. It is not directed at children and we do not knowingly collect anything from anyone.
If this changes materially — a different ad network, another third-party script, anything that alters what leaves your browser — this page gets updated and the date below changes with it. It is the page that tells you what the site actually does, so letting it go stale would defeat the point.
Why this page is longer than it needs to be. A privacy policy that says "we value your privacy" and then lists nine categories of shared data is not being honest with you. The trade here is simple and worth stating in full: the site is free, nobody selling materials pays for it, and the price of that is advertising you did not ask for and a consent prompt we did not want. Everything else — your measurements, what you calculated, what you were quoted — stays on your machine, because it never needed to be anywhere else.
Questions about any of it: the contact page. If something on this page is wrong or unclear, that is worth telling us about too.
Last updated 2 August 2026.
Change your advertising consent choices This link opens the consent prompt. It appears once advertising is switched on and you are in a region where consent applies.