What we do and don't collect

Your calculations

The calculation engines are JavaScript that runs on your device. When you change a design speed or a grade, no network request is made and nothing is transmitted. You can verify this by opening your browser's network panel and using the calculator — you will see no requests. You can also disconnect from the network entirely after the page loads and the calculators will keep working.

Calculator state is written into the page URL so a calculation is shareable. That URL stays in your browser unless you choose to share it. It is not sent to us, and the feedback form deliberately strips the query string before submitting.

Feedback you submit

When you use the feedback form, we store only:

• which calculator you were using
• whether you marked it useful
• the message you typed, if you typed one
• the path of the page, without the query string
• the time of submission

We do not store your inputs, your name, your email, or an account identifier, because there are no accounts. Please don't put personal or project-confidential information in the message field — it isn't needed, and we'd rather not hold it.

Your IP address is used transiently to rate-limit submissions and is not written to the database.

Analytics

We use Cloudflare Web Analytics, which is privacy-preserving: it sets no cookies, does not fingerprint visitors, and does not track people across sites. We use it to see which calculators get used so we know which ones to build next. There are no third-party advertising or tracking scripts on this site.

Cookies

We set no cookies. Your colour theme preference is stored in your browser's local storage and never leaves your device.