Privacy
Your numbers stay in your browser.
This policy explains what data this site collects, what it doesn't, and the handful of third parties that help keep the site online. Short version: your scenario inputs never leave your device.
Last updated: October 14, 2026
What we collect
Nothing from the calculator
All calculations run locally in your browser. Principal, rate, contributions, and every other input stay on your device and are never transmitted to us.
What's in the URL
Your scenario, by design
Scenario parameters are encoded in the URL so you can bookmark or share a result. If you share the URL, you're sharing those numbers — nothing is stored on our end.
What we don't do
No sign-up, no profiling
There are no accounts, no advertising networks, no cross-site trackers, and no attempt to identify you personally. We don't sell data because we don't have any.
The details
A longer, honest explanation.
- 01
Information you provide
The only time you share information with us is if you email us directly. In that case we see your email address and whatever you choose to send. We use it to reply and nothing else. We don't add your email to any list.
- 02
Local storage & cookies
We use a single localStorage entry to remember your light/dark theme preference across visits. No cookies are set by this site, and no third-party scripts read or write cookies on it.
- 03
Server logs
Our hosting provider keeps standard access logs (IP address, user agent, page requested, timestamp) for a short period for security and abuse prevention. These are not combined with any other data and are not used to profile visitors.
- 04
Analytics
If we use analytics in the future, it will be a privacy-respecting, aggregate-only tool (no cookies, no personal identifiers). We'll update this page before turning anything on.
- 05
Children's privacy
This site is intended for a general audience. We do not knowingly collect any personal information from children under 13.
- 06
Your rights
Because we don't maintain user accounts or a database of visitors, there's almost nothing to delete or export. If you've emailed us and want that correspondence removed, write to us and we'll delete it.
Changes to this policy
If we materially change how we handle data, we'll update this page and bump the "last updated" date at the top. Continued use of the site after a change means you accept the updated policy.
Questions? Contact us.
Start compounding, keep compounding.
Open the calculator, change one number, and watch the long tail.