A collection of useful calculators.
Everything here is computed in your browser and nothing you enter is sent anywhere. How your data is handled · Disclaimer
Compare paying extra on your mortgage vs. investing the difference. Models payoff timelines, net worth, and tax implications.
Compare the true cost of moving: monthly payment, lifetime interest, and how rate changes affect your buying power.
Compare job offers side by side over a multi-year horizon. Models take-home pay, bonuses, retirement contributions, and what you keep if you leave early.
Compare cost and return of home and small-commercial solar, wind, and battery systems under your utility's actual rates.
These calculators have no server behind them. Every figure is computed in your browser from what you type, and none of them makes a network request of any kind with your data. There is no account, no login, and no submit step.
This index page stores nothing. Each calculator saves your inputs in that browser's local storage on the device you are using, so your work survives a reload. It stays on the device until you clear it, and it is not synced or backed up anywhere. Every calculator names its own storage keys in its own copy of this notice and offers a button to delete them.
Where a calculator offers a share link, that link contains your inputs encoded into the URL itself. The data travels wherever you send the link, and it is encoded rather than encrypted, so anyone holding the link can read it. Anything that handles a URL may also retain it, including chat and email services, browser history, and server logs. Treat a share link as you would a document containing the figures in it, because that is what it is.
There is no analytics, no cookies, no tracking pixels, no third-party scripts, and no externally loaded fonts. These pages use only fonts already on your system.
The site is static files served by GitHub Pages. Whoever serves them can see that a browser requested a page, along with the usual things any web server records such as an IP address and a timestamp. They cannot see what you typed, because it never reaches them.