Privacy Policy

Last updated: 2026-08-10.

What this site is

This site is a static website: every calculator runs entirely in your browser, and no dimension, species selection, or calculation result you enter into a tool is ever transmitted to a server for processing. The calculators work by running the same open math described throughout the reference pages directly on your device.

Information we collect

Analytics. We use privacy-respecting analytics (Vercel Web Analytics, which does not use cookies or collect personally identifiable information) to understand which pages and tools are used, so we can prioritize which reference content and calculators to expand. Where active, we also use Google Analytics (GA4), configured without persistent cookies or client-side storage (client_storage: 'none'): it does not set the _ga cookie GA4 uses by default and does not store an identifier that could recognize you on a later visit. Because no persistent cookie is set, GA4 here does not require its own cookie-consent banner beyond what is disclosed on this page.

Newsletter. If you sign up for email updates, we collect the email address you provide and store it with our email service provider (Brevo) to send you the updates you signed up for. You can unsubscribe at any time via the link in every email we send.

Contact form / email. If you contact us by email or through a contact form, we collect whatever information you choose to include (your email address and message) solely to respond to you.

Payments. If you purchase the Shop Reference Pack or make a donation, payment is processed entirely by Stripe. We do not receive, see, or store your card number, expiration date, or CVC — Stripe handles that directly and is subject to its own privacy policy and PCI-DSS compliance obligations.

Advertising

We may display advertising, including through Google AdSense, to help support the cost of researching and publishing this site's reference content. If and when advertising is active, this section will name the specific network, disclose that cookies may be used to personalize ads based on your visits to this and other websites, and link to Google's Ads Settings and the industry opt-out at aboutads.info. Nothing on this site currently precludes carrying advertising in the future.

Cookies

Analytics on this site does not set cookies: Vercel Web Analytics is cookieless by design, and GA4, where active, is configured without persistent cookies or client-side storage as described above. If advertising is active in the future, this section will name any cookies that feature adds for ad personalization. We do not use cookies to track you across unrelated third-party sites for purposes beyond what is disclosed here.

Third-party services

This site may link to, or embed functionality from, third-party services including Stripe (payments), Brevo (email), Google Analytics/AdSense (analytics/advertising, where active), and the sister sites listed in our footer. Each of those services has its own privacy policy governing how it handles your data once you interact with it directly.

Data retention

Newsletter email addresses are retained until you unsubscribe. Contact-form or email correspondence is retained as long as reasonably necessary to resolve your inquiry and for our own recordkeeping. Analytics data is retained according to the relevant provider's standard retention policy (Vercel Analytics and, where active, Google Analytics).

Children's privacy

This site is not directed at children under 13, and we do not knowingly collect personal information from children under 13.

Your choices

You can decline cookies via your browser settings (this may affect analytics but will not affect the calculators, which run without any cookies or server round-trip). You can unsubscribe from our newsletter at any time. You can request that we delete any contact-form correspondence we hold by emailing us.

Changes to this policy

We may update this policy as the site's features change — most notably as analytics, advertising, or monetization features described above move from planned to active. The "Last updated" date at the top of this page reflects the most recent revision; material changes will be reflected here, not announced separately.

Contact

Questions about this policy can be sent to the email address on our contact page.