Each calculator uses a documented formula and displays important limits alongside its estimate. The model does not silently change when a visitor selects a display currency or country filter.
General formulas and regional models
Most tools use general mathematical models and the rate, period, amount, and timing entered by the visitor. The Canadian mortgage renewal tool is a separate regional model: it converts the entered Canadian quoted rate using the chosen compounding convention, defaulting to semi-annual, and compares payments and balances over the entered term. The U.S. mortgage discount-points tool separately models entered points and loan assumptions. Regional labels do not imply a broader set of country rules.
Inputs, rates, and currency
Rates are user-entered assumptions, not live market data or recommendations. Currency selectors control display formatting only; no exchange-rate conversion occurs. A country filter changes which tools appear and does not convert values, alter a formula, or establish tax residence.
What is excluded
Unless a calculator explicitly models an item, do not assume taxes, insurance, utilities, fees, lender rules, government benefits, account eligibility, or legal limits are included. Principal-and-interest estimates are not total housing costs. Each tool lists its own assumptions and exclusions.
Sources, automated checks, and review
Tool pages show model methods, listed sources, and an applicable source/rule year where relevant. Automated reference, edge-case, and browser tests help check implementation; they are not a substitute for qualified professional review, and no professional review is claimed.
Corrections
Review the method and assumptions shown on each tool. If something appears wrong, use the contact page to prepare an email draft. It is not sent automatically, and a response is not guaranteed.