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.
Free to use No sign-up needed Updates as you type
Default interest rate: 7.18% — Freddie Mac 30-year fixed average, week of Nov 5, 2026. Enter the rate from your own Loan Estimate.
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. To build the same table yourself, there is a printable amortization worksheet with a spreadsheet template.
Worked example: with loan amount of $320,000, interest rate of 7.18% and loan term of 30 years, the amortization calculator shows monthly payment of $2,167.79.
- Principal & interest
- $2,167.79
- Total interest
- $460,405
- Total of payments
- $780,405
- Payoff time
- 30 yrs
| Loan amount | Monthly payment |
|---|---|
| $80,000 | $541.95 |
| $200,000 | $1,354.87 |
| $350,000 | $2,371.02 |
| $600,000 | $4,064.61 |
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.
How every calculator here computes, what it assumes and how the defaults stay current: our methodology.
- 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 my information saved or shared?
No. Every calculation runs entirely in your browser. We never store, transmit or sell the numbers you enter.
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.
Sources
- Freddie Mac — Primary Mortgage Market Survey (weekly average rates)
- CFPB — Loan Estimate explainer
- CFPB — Fixed-rate vs adjustable-rate mortgages
How the figures on this site are calculated and tested: methodology · editorial policy.
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