Finance

This category covers the financial calculations that usually require either a spreadsheet, a phone call to a bank, or trusting a number you can't verify. A mortgage payment, a car lease breakdown, whether renting or buying makes more sense for your situation, how quickly compound interest actually grows your savings, and how far away financial independence really is — each of these has an established formula behind it, and each tool here shows that formula rather than hiding it behind a black-box result.

A few ways people commonly use these tools together: run the Mortgage Calculator and Buy vs Rent Calculator side by side when deciding whether to buy a home; check the Refinance Mortgage Calculator if you already have a mortgage and a lower rate becomes available; use the Compound Interest Calculator to sanity-check a savings goal before plugging the same assumptions into the FIRE Calculator; or compare the Car Lease Cost Calculator against the Auto Loan Calculator before a car purchase to see which financing path actually costs less over time.

None of these tools store what you enter — every calculation runs locally in your browser — and none of them substitute for advice from a licensed financial advisor, especially for decisions involving large sums or complex tax situations. See each tool's own page for the specific formula and assumptions it uses.