Loan & Mortgage Calculator
See your monthly payment, total interest, and full amortization schedule — and how much extra payments could save you.
Loan details
Principal vs. interest
Remaining balance over time
How this loan calculator works
Enter your loan amount, interest rate, and term, and the calculator instantly works out your fixed monthly principal-and-interest payment, the total interest you'll pay over the life of the loan, and a full amortization schedule showing how your balance declines over time. It works equally well for a mortgage, auto loan, personal loan, or student loan — anything with a fixed rate and a fixed term.
The formula
Lenders use standard amortization math, so the numbers here will match your loan documents:
M is your monthly payment, P is the loan principal, r is your monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments (years × 12). Each payment is split between interest — charged on the remaining balance — and principal; early payments are mostly interest, and that ratio flips as the balance shrinks.
What extra payments actually do
Every extra dollar you send in a given month is applied straight to principal, which lowers the balance that future interest is calculated on. That compounds: paying $200/month extra on a 30-year mortgage often trims several years off the loan and saves tens of thousands in interest, even though the extra amount looks small next to the loan balance. Toggle it on above to see your own numbers side by side.
Also useful: Auto Loan Calculator and Debt Payoff Calculator.
Frequently asked questions
No — this calculates principal and interest (P&I) only, which is what the loan formula itself determines. For a mortgage, add your estimated property tax, homeowners insurance, and any HOA dues on top of the number shown here to get your full monthly housing payment.
The interest rate is what's used to calculate your payment. APR also folds in lender fees and closing costs, spread over the loan term, so it's usually slightly higher — use APR here for the most realistic long-term cost comparison between offers.
Interest is charged on whatever balance remains, and early on that balance is largest, so interest takes the biggest bite. As you pay down principal, the balance — and the interest charged against it — shrinks, so more of each fixed payment goes to principal over time. That's normal amortization, not a sign anything's wrong.
This calculator assumes a fixed rate for the full term. For an ARM, use it to model each rate period separately (starting balance, that period's rate, and its remaining term) since the payment will recalculate whenever the rate resets.