Mortgage Calculator
Calculate your mortgage payment, total interest, and payoff timeline. See how down payment and term affect borrowing cost before you buy.
Understanding Mortgage Payments and Borrowing Cost
A mortgage is usually the largest loan you'll ever take — and the interest cost over 15 or 30 years can exceed the home price itself. Before you shop for a home, knowing your true monthly payment and lifetime borrowing cost helps you borrow responsibly and avoid stretching beyond your budget.
Your mortgage payment depends on four variables: loan amount, interest rate, term length, and whether you make extra payments. A $350,000 home with 20% down at 6.75% over 30 years produces a very different outcome than the same home with 5% down on a 15-year term. This calculator shows both the monthly payment and the total interest so you can compare scenarios.
Mortgage math uses fixed-rate amortization: early payments are mostly interest, and later payments shift toward principal. That's why extra payments in the first few years save disproportionate interest — and why refinancing or shortening your term can save tens of thousands of dollars.
Use this calculator alongside your debt-to-income ratio and budget tools. Lenders typically want housing costs below 28% of gross income and total debt below 36%. If your mortgage pushes you above those thresholds, you may struggle to qualify — or to pay down other high-APR debt.
How These Calculations Work
Transparent methodology — no black boxes. Here's exactly what happens when you use this calculator.
- 1
Enter home price, down payment, interest rate (APR), and loan term.
- 2
Loan amount = home price minus down payment.
- 3
Monthly payment uses standard fixed-rate amortization (same formula lenders use).
- 4
We simulate each payment period to calculate total interest and payoff date.
- 5
Results include an amortization schedule so you can see principal vs interest over time.
Frequently Asked Questions
We use the standard amortizing loan formula: monthly payment = principal × [r(1+r)^n] / [(1+r)^n − 1], where r is the monthly interest rate and n is the number of payments.
No — this calculator shows principal and interest only. Property taxes, insurance, and PMI are separate costs that affect your total housing payment.
A larger down payment reduces your loan amount, which lowers both your monthly payment and total interest paid over the life of the loan.
A 15-year term has higher monthly payments but significantly less total interest. Compare both in this calculator alongside your debt-to-income ratio and budget.
Your mortgage is often your largest debt. Understanding its cost helps you decide whether to prioritize extra mortgage payments vs high-APR consumer debt.
Related Tools & Resources
Debt-to-Income Ratio Calculator
Check if your housing payment fits lender DTI guidelines.
Budget Calculator
See how a mortgage payment fits your monthly cash flow.
Refinance Calculator
Compare refinancing savings after closing costs.
Debt-Free Date Calculator
Include your mortgage in a full debt payoff timeline.