Amortization Calculator
Generate a full loan amortization schedule and see your monthly payment, total interest, and payoff timeline
Last updated: 2026-07-18
Amortization is the process of paying off a loan through regular, fixed payments over time, with each payment split between interest and principal. Our free amortization calculator works for any installment loan -- auto loans, personal loans, student loans, or a mortgage -- and shows the full month-by-month breakdown, not just a single monthly payment figure, so you can see exactly how much of each payment chips away at your balance versus covering interest.
Amortization Payment Formula
O(n) schedule generationM = monthly payment · P = loan principal · r = monthly interest rate · n = number of payments
Here, r is the annual interest rate divided by 12 (monthly rate), and n is the loan term in years multiplied by 12 (total number of monthly payments). Each month, the interest portion is the current balance times r; the rest of the fixed payment reduces principal, which is why the interest/principal split shifts over the life of the loan even though the payment itself stays constant.
Use Cases
Auto Loan Payoff Planning
See your monthly car payment and how quickly the loan balance drops.
Personal Loan Comparison
Compare total interest cost across different loan terms and rates.
Student Loan Payoff Timeline
Understand how much of each payment goes to interest early in repayment.
Early Payoff Analysis
Use the full schedule to see the remaining balance at any point in time.
Refinancing Decisions
Compare an existing loan's remaining schedule against a new loan offer.
Frequently Asked Questions
Why does the interest portion of my payment shrink over time?
Interest is charged on the remaining balance, so as principal is paid down each month, the balance -- and therefore the interest charged on it -- gets smaller, and more of each fixed payment goes toward principal.
Does a longer loan term always cost more in total interest?
For the same rate and loan amount, yes -- a longer term lowers the monthly payment but increases the number of payments and the total interest paid over the life of the loan.
What happens if I make extra principal payments?
Extra payments applied to principal reduce the balance faster, which shrinks all future interest charges and shortens the payoff timeline -- this calculator shows the standard schedule without extra payments.
Is this the same as a mortgage calculator?
The math is identical, but this calculator takes the loan amount directly, so it works for any amortizing installment loan, not just a home purchase with a price and down payment.
Why is the last payment a different amount?
Rounding each month's interest and principal to the cent can leave a few cents of drift by the final payment, so the last payment is adjusted to pay off the exact remaining balance instead of the fixed monthly amount.
References
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