Privacy policy

Short version: the calculators run in your browser. We do not collect, upload or store the ages, heights, weights or any other numbers you type into them. We do use Google Analytics to count visits and see which calculators get used, and Microsoft Clarity to record how pages are used with the calculator inputs and results masked; details are under Analytics and Session recordings below.

Calculator inputs

When you press a calculate button, the math (mid-parental height, the Khamis-Roche prediction, growth-chart percentiles) happens locally with JavaScript. Your inputs stay on your device and are not sent to us.

No accounts

There is no sign-up and no login.

Analytics

We use Google Analytics 4 to count visits and see which pages and calculators are used. Google Analytics sets first-party cookies (such as _ga) and receives standard usage data: the page viewed, the referring page, browser and device type, approximate location derived from your IP address, and the time of the visit. When you run a calculator we record only that a calculation was run, which calculator it was and which method produced the result. The ages, heights and weights you type are not included. When a contact message is sent we record the chosen topic, not the message. Google’s handling of this data is described in its policy for sites that use its services, and you can opt out with the Google Analytics opt-out browser add-on.

Session recordings (Microsoft Clarity)

We use Microsoft Clarity to see how pages are used, for example where people scroll, which buttons they press and where a layout breaks. Clarity sets first-party cookies (such as _clck and _clsk) and receives: the page address, the referring page, clicks, taps, scrolling and pointer movement, window size, device and browser type, an approximate location derived from your IP address, and the structure and fixed text of the page.

What Clarity does not receive. On every page that has a calculator, a quiz or a form, the whole page is marked as masked and only fixed text (the site header, the introduction, the article and FAQ section, the related links and the footer) is left readable. Inside the masked area Clarity’s script replaces every character with a placeholder in your browser, before anything is sent. That covers the sex, age, height and weight you enter, the parents’ heights, every result, range, percentile and table the calculators produce, and anything typed into the contact form. Those values are not sent to Clarity and cannot be read in a recording.

A recording does keep the page’s layout: the outline of a result box, how many rows a result table has and how long a masked word or number is, but not its letters or digits. Clarity is not loaded at all when the page address carries extra parameters other than standard campaign tags. We do not use Clarity to identify visitors and we do not send it any health information. Microsoft’s handling of this data is described in the Microsoft Privacy Statement.

Children’s data

Because calculator inputs are never transmitted, no information about a child (age, height or weight) is collected by this site.

Contact form

If you send a message through the contact form, we store the topic, the optional page name, the message text and the time it was sent, so that we can read it. The form does not ask for your name or contact details. Please do not put personal or health information in a message. If you e-mail us instead, we receive your e-mail address and whatever you write, and use them only to answer you.

Advertising

This site may display ads from a third-party ad network to keep it free. Ad providers may use cookies or similar technologies as described in their own policies. Ad code runs in marked ad slots and is not given the values you enter into the calculators.

Server logs

The hosting provider (Cloudflare) may keep standard access logs (IP address, time, requested file) for security and abuse prevention. These are not combined with calculator inputs, which never reach the server.

Questions: use the contact form.