Privacy Policy

Last updated October 2, 2026

Your calculator inputs

Everything you type into the calculator (prices, rent, income, ZIP code and so on) is processed on your own device. So that your numbers are still there next time, they are saved in your browser's local storage on that device. They are not sent to us. You can clear them at any time with Reset assumptions, or by clearing this site's data in your browser.

Shared links

When you click Share, the calculator builds a link that contains your current settings and a short result code (for example, that renting won 66% of historical windows). Anyone you give the link to can see those settings. Apps that show link previews (such as iMessage, Slack or X) fetch the link to build the preview.

To understand how the site is used, we count a few events related to sharing:

• when someone uses the Share button, and how (copied, share sheet or address bar);
• when an app builds a preview of a shared link, and which app;
• when someone opens a shared link, and the website it came from (the site's domain name only, not the full address).

Each count stores only the event, the result code, the details listed above and the country the request came from. It does not store your IP address, your calculator inputs or any identifier, and it does not use cookies. These counts are stored with Cloudflare Workers Analytics Engine and are only visible to us.

Contact form

If you write to us through the contact page, we receive your name, email address and message by email, plus a link to your calculator settings if you leave that box ticked. We use this only to reply to you and to improve the calculator, and we don't add you to any mailing list. To prevent abuse, the form is limited to a few messages per minute from one IP address; that check is done by Cloudflare and the address isn't stored with your message.

The contact page uses Cloudflare Turnstile to check that messages come from people, not bots. Turnstile runs only on the contact page and collects information about your browser and device to do that check; see Cloudflare's Turnstile privacy addendum.

Services we use

• Cloudflare hosts the site and delivers every page. Like any web host, it processes your IP address and basic request information to deliver pages and protect the site from attacks. See Cloudflare's privacy policy.
• Google Fonts supplies the typefaces. Your browser downloads them from Google's servers, which see your IP address. See Google's privacy policy.

We don't use advertising networks, analytics trackers or social media pixels, and we don't sell or rent personal information to anyone.

Cookies

This site doesn't set cookies. Cloudflare may set a strictly necessary security cookie in some cases (for example, when it challenges suspicious traffic), and Turnstile may use similar browser storage on the contact page to do its check.

Children

The site is intended for adults and is not directed at children under 13. We don't knowingly collect personal information from children.

Your choices and rights

You can use the calculator without giving us any personal information. If you've written to us and want a copy of your message or want it deleted, contact us and we'll take care of it. Depending on where you live, you may have additional rights over your personal information, and we'll honor requests made under those laws.

Changes

If we change how the site handles information, we'll update this page and the date at the top.

Contact

Questions about this policy? Reach us through the contact page.