Privacy Policy

Last updated: 1 October 2026

Short version: your calculator inputs never leave your browser. We use Google Analytics 4 to count which pages and calculators get used, but only if you click “Accept analytics” on the cookie banner. You can change your choice anytime from the “Cookie settings” link in the footer.

What we collect

Without your consent, nothing that identifies you. This is a static website with no accounts, no sign-up, and no contact form, so we never ask for your name, email, or any personal details to use the tools. If you accept analytics, Google Analytics collects the usage data described below, which still does not identify you personally.

Calculators run in your browser

Every calculation happens locally in your browser. The values you enter, wall dimensions, block sizes, and the like, are never transmitted to us or to Google, and are not saved. Refresh the page and they are gone. We never send your inputs to analytics: there are no custom events that carry what you typed.

Analytics and cookies

We use Google Analytics 4 (measurement ID G-GBMK69820R), and only if you click “Accept analytics” on the banner. Decline and nothing loads from Google and no analytics cookie is set.

When you accept, Google Analytics collects:

• pages viewed and the site that referred you;
• your approximate location (country and city derived from your IP address; GA4 does not store IP addresses);
• your device type, browser, and screen size;
• how long you spend on a page.

It does not receive anything you type into a calculator.

Cookies:

• Only after you accept analytics: _ga and _ga_<container-id>, set by Google Analytics. These are first-party cookies and expire after up to two years.
• Always, as a strictly necessary cookie: ttc_consent, which only records whether you accepted or declined analytics so we do not ask again. It stores no personal data and expires after 180 days.

Google acts as our data processor for analytics. See Google’s privacy policy, and if you want to opt out across all websites, the Google Analytics opt-out browser add-on.

Changing your choice: use the “Cookie settings” link in the footer at any time. Switching from accept to decline deletes the Google Analytics cookies from your browser.

Data retention: analytics data is retained for 14 months and then deleted automatically.

Email

If you email us (see the contact page), we receive whatever you send and use it only to respond. We do not add you to a mailing list.

Third-party links

We link to source documents on external sites, such as standards bodies and manufacturers. Those sites have their own privacy practices, which we do not control.