This page describes what actually happens when you use this site. It is written against what the code does, and it is updated when the code changes.
What the site itself collects
Nothing you type into a calculator leaves your browser. Every calculator on this site runs entirely client-side: the inputs, the arithmetic and the result all happen on your device, and no part of it is sent anywhere. There is no server that sees your printer, your material or your electricity rate.
The site is statically generated and served as files. There is no account system, no login, and no user profile.
Analytics
The site uses Google Analytics 4 to understand which pages are read and how people arrive. GA4 sets cookies and collects an approximate location, device and browser information, and the pages visited.
There is no cookie banner here, and analytics loads on every page as it opens. That is stated plainly rather than hedged: nothing on this site asks your permission first, so the honest description is that measurement begins when the page does. You can stop it with your browser's cookie controls, with any content blocker, or with Google's own opt-out browser add-on, and nothing on the site stops working if you do.
The site also counts page views through its hosting platform, which does that without cookies and without identifying individual visitors. That count runs whatever you decide about the cookie above.
Advertising
This site may display advertising supplied by Google AdSense. Advertising cookies may be used to personalise the advertisements you see and to limit how often a given advertisement is shown to you.
You can review and change your advertising personalisation settings at Google's My Ad Center, and you can opt out of personalised advertising from participating vendors at aboutads.info. Where personalised advertising is served to a visitor in the European Economic Area or the United Kingdom, a consent message is shown first, as the law there requires.
Email and newsletter
If you subscribe to the newsletter, your email address is stored with our email provider for the purpose of sending you the newsletter and a welcome message. It is not sold, rented or shared. Every message includes an unsubscribe link, and unsubscribing removes you from the list.
If you use the contact form, your message and the address you supply are transmitted through a form-handling service so that a reply can be sent.
Payments
If you buy the downloadable pack or make a donation, the payment is processed by Stripe on Stripe's own pages. Card details are never entered on this site and never reach it. Stripe supplies a payment confirmation and the email address used for the receipt.
Cookies you can control
Analytics and advertising cookies are the only non-essential cookies used. The site sets no cookies of its own at all: it has no account system and no session, so everything in this section belongs to a third party. Blocking third-party cookies, or blocking those two domains specifically, removes them, and it does not restrict access to anything here — the calculators in particular never needed them, because they compute in your browser and store nothing.
Your rights
Depending on where you live you may have the right to request a copy of the personal data held about you, to have it corrected, or to have it deleted. In practice the only personal data this site holds directly is a newsletter subscription, and the contact page is the way to ask about it.
Changes
If the services used here change, this page is updated to match. Anything that would materially change what is collected will be reflected here before it takes effect.
Data retention, in plain terms
Analytics data is retained by the analytics provider under its own retention settings and is aggregated rather than tied to a name. Newsletter subscriptions are kept until you unsubscribe. Contact-form messages are kept as long as they are useful for answering you and are not added to any mailing list. Payment records are held by the payment processor, which is required to retain them for its own accounting and anti-fraud obligations.
Children
This site is aimed at people who own or use 3D printers. It is not directed at children, and no attempt is made to collect information from them.
International transfers
The analytics, email, payment and hosting providers used here operate internationally, which means data associated with your visit may be processed outside your own country. Each of those providers publishes its own terms covering how it handles such transfers.
Who to ask
Questions about anything on this page go to the address on the contact page, which reaches a person rather than a queue.