Amortization Calculator
Calculate your monthly payment and full amortization breakdown — principal, interest, and balance over time.
🧮
Enter your values and click Calculate
How It Works
Monthly payment: M = P × r(1+r)^n / ((1+r)^n − 1), where P = principal, r = monthly rate (annual ÷ 12), n = total months. Each month: interest = balance × r, principal = M − interest, new balance = balance − principal. Balance milestones are calculated by simulating each payment in sequence.
Examples
$300,000 at 7% for 30 years
A typical 30-year fixed-rate mortgage at a common modern interest rate.
Result: ~$1,996/month. ~$418,000 total interest paid. Balance after 5 years: ~$279,000.
$200,000 at 5.5% for 15 years
A 15-year mortgage showing the trade-off of higher payments for dramatically less total interest.
Result: ~$1,634/month. ~$94,000 total interest — roughly half of a 30-year equivalent.
$25,000 auto loan at 6.5% for 5 years
A new car loan showing typical auto financing costs.
Result: ~$489/month. ~$4,340 total interest over the loan term.
Frequently Asked Questions
Why do I pay so much interest at the start?
Early payments go mostly to interest because the outstanding balance is at its highest point. Each month's interest charge equals the remaining balance multiplied by the monthly rate, so as the principal decreases over time, the interest portion shrinks and more of your fixed payment reduces the principal. This is why making extra principal payments in the early years has an outsized impact on total interest paid.
What happens if I make extra payments?
Any extra principal payment directly reduces the balance, which lowers every future month's interest charge and shortens the overall loan term. On a 30-year mortgage, adding even one extra monthly payment per year can cut years off the term and save tens of thousands in interest. This calculator shows the baseline schedule; a dedicated extra-payment calculator can model the accelerated payoff.
How do I compare a 15-year vs 30-year mortgage?
Run this calculator twice with the same loan amount and rate but different term lengths. The 15-year loan will show a significantly higher monthly payment but dramatically lower total interest — often less than half. The break-even analysis depends on whether the payment difference could be invested elsewhere at a higher return than your mortgage rate.