Mortgage guide
A practical guide to mortgage payment formulas, principal and interest, down payments, PMI, taxes, insurance, and affordability planning.
Reviewed by FormatNest Editorial Team. Updated August 19, 2026.
A fixed-rate payment is usually calculated from the loan principal, periodic interest rate, and number of payments. The payment does not automatically include property taxes, homeowners insurance, HOA dues, or mortgage insurance, so compare the calculator result with your full monthly housing budget.
Start with Mortgage Calculator, then compare Loan Calculator, PMI Calculator, House Affordability Calculator, Escrow Calculator, and Mortgage Refinance Calculator. This gives you payment, upfront cash, recurring costs, and break-even context.
For a $300,000 home with $60,000 down, a 6.5% annual rate, and a 30-year term, the calculator can show principal-and-interest payment and total interest. Add taxes, insurance, HOA, and PMI separately before deciding what you can afford.
Confirm whether the rate is fixed or adjustable, which fees are included, whether the loan has points, how taxes are assessed, and whether your lender's APR differs from the note rate.