How this site handles your information, in plain language: almost nothing is collected, and the calculators collect nothing at all.
The calculators run entirely in your browser. Nothing you type into them is sent to us, stored, or shared. The site uses analytics to count visits in aggregate, and that is the extent of the data involved. There are no accounts, no newsletters and no sale of personal information — there is no personal information here to sell.
Every calculation on this site — rafter lengths, spans, sizes, angles — is performed locally on your device by the page's own code. Your spans, pitches and measurements never leave the browser, are not transmitted to any server, and are gone when you close the tab. We could not look at your project if we wanted to; the site is built so that there is nothing to look at.
The site is hosted on Cloudflare's static hosting platform. Like any web host, Cloudflare processes standard technical request data — such as IP address, browser type and the page requested — to deliver the site and protect it from abuse. That processing is governed by Cloudflare's own privacy policy. The site itself keeps no server-side database of visitors.
We use Google Analytics 4 to understand which calculators are used and which need improving. It is loaded through Cloudflare Zaraz, a tag manager that runs the analytics tag without this site setting its own tracking code. Analytics identifiers are pseudonymous: they let visits be counted and grouped without naming you, and we use the reports in aggregate — pages viewed, approximate region, device type — never to identify an individual reader.
The site itself sets no cookies. Google Analytics sets its standard first-party cookies to distinguish one visit from another; those are the analytics cookies described above. If advertising is enabled in future, the advertising section below explains the additional cookies that may then appear. Blocking cookies in your browser does not affect the calculators in any way.
When advertising is enabled on this site, Google AdSense may serve ads and set advertising cookies, and Google may use those cookies to personalise the ads you see; you can control ad personalisation in your Google Ads Settings. No advertising is currently served on this site.
If you use the report-an-error form or email us, we receive what you send: the calculator and inputs you chose to report, and your email address if you provide one or write by email. That information is used only to check the calculation and reply to you. It is not added to any mailing list and is not shared with third parties.
Questions about this policy go to Ian Welkins at ianwelkins@gmail.com.
This site is run by Ian Welkins, who is responsible for the limited personal data described in this policy and can be reached at ianwelkins@gmail.com.
You can ask at any time what personal data we hold about you — in practice, only emails and error reports you have sent us — and ask for it to be corrected or deleted. Write to the address above and it will be done. Analytics data is aggregated by Google and is not used to identify individual visitors.
This policy is effective from 30 October 2026.
If this policy changes — for example, if advertising is enabled — the updated text will be published on this page with the change reflected in the relevant section before or at the time it takes effect. The version published here is the current one.