Separate, tested calculation engines
The math for each calculator lives in its own small module, separate from the web page that displays it. The same module runs in automated tests and in your browser, so the numbers you see are the numbers that were tested.
Tests cover normal cases, zero and boundary values, invalid inputs and published reference results. Amortization schedules must pay the balance to zero, and principal plus interest must equal each payment.
Assumptions are part of the answer
Every calculator page lists what it includes and what it leaves out, such as fees, taxes or insurance. Precision is kept throughout the calculation, and amounts are rounded to cents only when they are displayed.
Estimates, not advice
Results are estimates based on the numbers you enter. They are not loan offers, approvals or financial advice, and a lender, bank or tax authority may calculate differently. We do not recommend specific lenders or products.
Your inputs stay in your browser
Calculations run on your device. The calculators do not send the numbers you enter to a server and do not require an account.