Mortgage / Loan Calculator
NewCalculate your monthly mortgage or loan payment, total interest, and full amortization schedule — with optional extra monthly payments.
| Year | Principal paid | Interest paid | Remaining balance |
|---|
Frequently Asked Questions
What formula calculates the base monthly payment?
The standard fixed-rate amortization formula: payment = P × r / (1 − (1 + r)^−n), where P is the loan principal, r is the monthly interest rate (annual rate ÷ 12 ÷ 100), and n is the total number of monthly payments (years × 12). If the rate is 0%, it falls back to a simple principal ÷ n split.
How does the "extra monthly payment" field affect the payoff time?
The extra amount is added on top of the calculated base payment every month, and the tool re-simulates the full amortization month-by-month with that higher payment — so you see the actual shortened payoff time and reduced total interest, not just an estimate.
Why does the yearly schedule table sometimes have a shorter final year?
When extra payments cause the loan to pay off partway through what would be the final year, that last row captures only the partial year of principal/interest actually paid before the balance reaches zero.
Is this specific to mortgages, or does it work for any amortizing loan?
It works for any fixed-rate amortizing loan — car loans, personal loans, and mortgages all use the same payment formula; just enter the relevant principal, rate, and term.
Are my loan numbers stored or sent anywhere?
No — every calculation, including the full amortization simulation, runs in your browser with plain JavaScript. Nothing is transmitted.
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