Amortization Calculator
Generate detailed amortization schedules showing principal and interest breakdown over time. Free, accurate, no signup.
Loan Details
Loan Amount & Terms
Total amount of the loan
Annual interest rate
Length of the loan
Payment Options
Additional payment per period
Amortization Analysis
Monthly Payment
Scheduled payment per period
Total Interest
Over life of loan
Total Payments
Number of payments
Principal vs Interest
Balance Over Time
Remaining principal after each scheduled payment.
Total Paid
Principal + Interest
Payoff Date
Final payment date
Payment Breakdown
Amortization Tips
- • Early payments go mostly toward interest, later payments toward principal
- • Extra principal payments can significantly reduce total interest
- • True bi-weekly payments follow roughly the same payoff schedule as monthly — choose Accelerated Bi-weekly (half the monthly payment, 26 times a year) to make the equivalent of 13 monthly payments and pay off years early
- • Consider refinancing if interest rates have dropped significantly
How it works
An amortization schedule breaks a fixed payment down, period by period, into interest and principal. Each period the lender charges interest on the current balance; the rest of your level payment reduces the principal. As the balance falls, the interest portion shrinks and the principal portion grows — which is why a schedule starts interest-heavy and ends principal-heavy.
Splitting each payment
Interestₖ = Balanceₖ₋₁ · r Principalₖ = M − Interestₖ Balanceₖ = Balanceₖ₋₁ − Principalₖ
- M
- the fixed payment = P · r(1+r)ⁿ / [(1+r)ⁿ − 1]
- r
- periodic interest rate
- Balanceₖ
- remaining principal after payment k
Worked example
- $200,000 loan at 6% → r = 0.5%/month, payment M ≈ $1,199
- First payment, balance = $200,000
- Interest = 200,000 × 0.005 = $1,000
- Principal = 1,199 − 1,000 = $199
Payment 1 is $1,000 interest / $199 principal; by the final payment it's almost entirely principal.
Good to know
- Extra payments apply directly to principal, so they skip the interest on every remaining period — the earlier you make them, the more they save.
- Interest-only or balloon loans don't amortize fully: the balance doesn't reach zero on schedule, leaving a lump sum due at the end.
- The "halfway point" in time is not the halfway point in equity — on a 30-year loan you don't cross 50% paid-off until ~year 19.
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Frequently Asked Questions
Why do early loan payments go mostly toward interest?
Interest is charged on the remaining balance each period, and at the start of the loan the balance is at its largest. On a $300,000 loan at 6.5%, the first monthly payment of $1,896 includes $1,625 of interest and only $271 of principal. As the balance falls, the interest portion shrinks and more of each level payment goes to principal — the schedule flips to mostly principal in the later years.
How much can extra payments save on a mortgage?
Extra payments apply directly to principal, so they eliminate the interest that balance would have accrued over every remaining period. On a $300,000, 30-year loan at 6.5%, an extra $200 per month saves roughly $100,000 in interest and pays the loan off about 7 years early. The earlier in the loan you make extra payments, the more interest each dollar saves.
What is the difference between bi-weekly and accelerated bi-weekly payments?
True bi-weekly payments split the loan into 26 smaller payments per year sized to follow the same payoff schedule as monthly payments. Accelerated bi-weekly payments take half the monthly payment and pay it 26 times a year — the equivalent of 13 full monthly payments annually — which pays the loan off years earlier and saves significant interest.
How does a balloon loan differ from a fully amortizing loan?
A fully amortizing loan reaches a zero balance at the end of its term. A balloon loan uses a lower periodic payment that does not fully retire the principal, leaving a large lump sum — the balloon — due at maturity. The amortization period (used to size the payment) is longer than the actual loan term, so borrowers must plan to refinance, sell, or pay the balloon when it comes due.