Amortization Calculator
Build a complete amortization schedule for any fixed-rate loan — see every payment split into principal and interest, and how extra payments shorten the term.
How the amortization calculator works
This calculator builds the full payment-by-payment schedule for any fixed-rate loan from three inputs: the amount borrowed, the annual rate, and the term. It computes one level payment, then walks the loan forward month by month. For each period it charges interest on the current balance, applies whatever is left of the payment to principal, and carries the reduced balance into the next row.
The result is a complete table showing how interest and principal trade places over time and how the balance falls to zero on the final payment. Adding an optional extra amount pushes the payoff earlier and lowers total interest.
Worked example: with loan amount of $320,000, interest rate (apr) of 6.75% and loan term of 30 years, the amortization calculator shows monthly payment of $2,075.51.
- Principal & interest
- $2,075.51
- Total interest
- $427,185
- Total of payments
- $747,185
- Payoff time
- 30 yrs
| Loan amount | Monthly payment |
|---|---|
| $80,000 | $518.88 |
| $200,000 | $1,297.20 |
| $350,000 | $2,270.09 |
| $600,000 | $3,891.59 |
The formula
Each period: interest = balance × r, principal = M − interest, new balance = balance − principal, where r is the annual rate ÷ 12 and the level payment M = P × r ÷ (1 − (1 + r)^−n). Repeat for all n periods until the balance reaches zero.
- Assumes a fixed rate and a fully amortizing loan that reaches a zero balance on the final scheduled payment.
- Works for mortgages, auto loans, or any installment debt — but it ignores fees, escrow, and insurance that may ride alongside the payment.
- Interest is calculated on the period balance using simple monthly compounding; loans using daily interest accrual will differ slightly.
- Extra payments are assumed to post to principal immediately; if your servicer holds or misapplies them, real savings can fall short.
- Does not model rate changes, recasts, skipped payments, or late fees — confirm those terms in your note before relying on the schedule.
Results are estimates for educational purposes and are not financial advice. Confirm exact figures with your lender or a licensed advisor.
Questions about the amortization calculator
What is the difference between the loan term and the amortization period?
For most fixed-rate mortgages they match — a 30-year term amortizes over 30 years. They diverge on balloon or some commercial loans, where payments are sized for a long amortization (say 30 years) but the full balance comes due at a shorter term (say 7 years). This calculator assumes term and amortization are the same.
Can I use this for a loan I've already been paying for years?
Yes — enter your current balance as the amount, your actual rate, and the months remaining as the term. The schedule then projects forward from today rather than from the original closing.
The interest-versus-principal split will reflect where you stand now, which is further along than a brand-new loan of the same size.
How does an extra payment change the schedule's shape?
It pulls every future row forward. Because the extra amount reduces the balance immediately, the next month's interest is calculated on a smaller number, so slightly more of your regular payment also goes to principal.
The effect compounds, the table ends sooner, and the total interest column lands lower than the original plan.
Is the Amortization Calculator free to use?
Yes. Every calculator on MortgageLoansCalculator is completely free, with no sign-up, login or paywall. Run as many scenarios as you like.
What is an amortization schedule?
It is a table showing every payment over the life of the loan — how much goes to interest, how much to principal, and the balance after each one.
Early payments are mostly interest and later ones mostly principal, laid out month by month.
How do extra payments affect amortization?
Any extra applied to principal immediately lowers the balance interest is charged on, so it cuts total interest and shortens the schedule — often by years — without changing your required payment. Test any amount above to see the new payoff date.
Mortgage Calculator
Estimate your monthly principal-and-interest payment and see a full amortization schedule for any home loan.
Mortgage Calculator with Taxes & Insurance
See your full PITI payment: principal, interest, property tax, homeowners insurance, PMI and HOA dues.
Mortgage Calculator with PMI
Include private mortgage insurance in your payment and find out exactly when PMI drops off.
APR Mortgage Calculator
Convert a rate plus points and fees into the true annual percentage rate (APR) of your mortgage.
Interest-Only Mortgage Calculator
Compare the low interest-only payment with the jump once principal repayment begins.
Biweekly Mortgage Calculator
Pay half your mortgage every two weeks and see how one extra payment a year cuts your term and interest.