How this mortgage calculator works
Your monthly repayment uses the standard amortization formula:
M = P × r ÷ (1 − (1 + r)⁻ⁿ)
- P — loan amount (principal)
- r — monthly interest rate (annual rate ÷ 12)
- n — number of monthly payments (years × 12)
Worked example
A $300,000 loan at 6% over 30 years works out to roughly $1,798.65 per month — about $647,515 paid in total, of which ~$347,515 is interest.
Frequently asked questions
- Does this include taxes and insurance?
- No — it estimates principal and interest only. Property tax, home insurance and lender fees are additional.
- Why does a small interest-rate change matter so much?
- Interest compounds over hundreds of payments, so even a 0.5% difference can change the total cost by tens of thousands of dollars over 30 years.
- Can I pay off my mortgage faster?
- Yes — extra monthly payments reduce the principal and cut total interest. A dedicated extra-payment calculator is coming to this family.