Privacy policy
The short version: the calculators run in your browser, there are no accounts, and nothing you type is sent to us.
Last updated 14 August 2026
What runs where
Every calculator on this site is JavaScript running on your own device. The numbers you type stay in the page. They are not transmitted to a server, not logged, and not stored.
Some pages put your numbers in the address bar, for example ?p=15&x=200. That is so you can bookmark a calculation or send it to someone. The address bar is part of the page, not a message to us — but remember that anything in a link you share travels with the link.
Cookies
This site sets no cookies of its own. Nothing here needs to remember who you are between visits, so there is no cookie banner to dismiss.
Analytics
We count page views with Fathom Analytics. Fathom is a privacy-first service: it sets no cookies, collects no personal data, and does not follow you to other sites. We see totals — how many people opened a page and roughly where in the world they were — never individuals.
The feedback form
If you send us a message through the feedback form, we receive what you wrote, and — because it is the difference between a bug we can reproduce and one we cannot — your browser and operating system, your screen size, your language and time zone, and the page you were on. Your email address is optional, and is used only to reply to you.
Messages are delivered to our own inbox and to a private team channel. They are not published, sold, or used for marketing.
Hosting and server logs
The site is served by Cloudflare. Like any web server, Cloudflare processes the IP address of every request in order to deliver the page and to block abuse. We do not build profiles from those logs. A submission from the feedback form is rate-limited by IP address for ten minutes, in memory only.
Children
The site is a general-audience tool and is not directed at children. It asks for no personal information from anyone.
Changes
If this policy changes, the date at the top of this page changes with it. There is no mailing list to notify, because there is no mailing list.
Contact
Questions about any of the above go through the feedback form.