Amortization Calculator
Understand your loan payments with ToolYard's free Amortization Calculator. Enter your loan amount, interest rate, and term to instantly generate a complete amortization schedule. You'll see how each payment divides between principal and interest, and how extra payments can shorten your term. Ideal for mortgages, auto loans, and personal loans, this calculator provides a clear picture of your repayment path — including total cost, payoff date, and balance over time. The tool generates a month-by-month breakdown showing payment number, date, principal and interest portions, and remaining balance. Visualize your loan balance reduction with an interactive chart. Add extra monthly payments to see dramatic interest savings and accelerated payoff dates. Choose between monthly, bi-weekly, or yearly payment frequencies. All calculations use standard loan amortization formulas with proper handling of interest compounding. Everything runs locally in your browser with complete privacy.
What Is an Amortization Calculator?
An amortization calculator generates a complete loan payment schedule showing how each monthly payment is divided between principal and interest over the full loan term. The core insight is counterintuitive: in the early years of a 30-year mortgage, the vast majority of your payment goes to interest, not equity. On a $360,000 loan at 7%, your first payment of $2,395 sends $2,100 to the lender as interest and only $295 toward reducing your balance. By month 240 (year 20), that split has shifted to roughly $1,400 interest and $995 principal. The schedule makes this visible — which is why it's one of the most useful tools in personal finance.
How to Use This Amortization Calculator
Enter your loan amount (the amount borrowed, not the purchase price), annual interest rate, and loan term in years. The calculator generates the full monthly payment, total interest over the life of the loan, and an amortization table. You can also enter an extra monthly payment to see how much time and interest you'd save by paying down principal faster. This is especially useful for new homeowners deciding whether to invest surplus cash or pay down the mortgage.
Worked Example: Daniel's $320,000 Mortgage at 6.8%
Daniel closed on a $320,000 mortgage at 6.8% for 30 years. His monthly P&I payment is $2,091. In month 1, $1,813 goes to interest and just $278 reduces principal. At this rate, by the end of year 1 he will have paid $25,092 but only reduced his balance by $3,460 — the other $21,632 was pure interest.
Monthly Payment: $2,091
Loan: $320,000 | Rate: 6.8% | Term: 30 years
Total Interest: $433,760 | Total Cost: $753,760
Adding $300/month extra cuts payoff to 22 years and saves $127,000 in interest
Year-by-Year Amortization Snapshot — $320,000 at 6.8%
| Year | Annual Payment | Principal Paid | Interest Paid | Remaining Balance |
|---|---|---|---|---|
| 1 | $25,092 | $3,460 | $21,632 | $316,540 |
| 5 | $25,092 | $5,020 | $20,072 | $299,780 |
| 10 | $25,092 | $7,200 | $17,892 | $271,640 |
| 15 | $25,092 | $10,240 | $14,852 | $232,040 |
| 20 | $25,092 | $14,560 | $10,532 | $175,800 |
| 25 | $25,092 | $20,720 | $4,372 | $95,400 |
| 30 (Final) | $25,092 | $95,400 | $680 | $0 |
Amortization Formula and Key Concepts
The monthly payment formula is: M = P × [r(1+r)⊃n] ÷ [(1+r)⊃n − 1] where P = principal, r = monthly interest rate (annual rate ÷ 12), and n = total number of payments. For Daniel's loan: P = $320,000, r = 0.068/12 = 0.005667, n = 360. The formula yields $2,091. Each month, the interest portion = remaining balance × r. Principal portion = payment − interest.
Negative amortization occurs when your payment is smaller than the monthly interest charge — the balance actually grows. This happens with some adjustable-rate and interest-only loans. A standard fully-amortizing loan eliminates this risk because every payment covers at least the interest plus some principal.
How Extra Payments Affect Amortization
| Extra Monthly Payment | Loan Payoff | Total Interest | Interest Saved |
|---|---|---|---|
| $0 (standard) | 30 years | $433,760 | — |
| +$100/month | 27 years 4 months | $386,400 | $47,360 |
| +$200/month | 25 years 1 month | $346,800 | $86,960 |
| +$300/month | 23 years 2 months | $313,200 | $120,560 |
| +$500/month | 20 years 3 months | $261,600 | $172,160 |
Tips for Reading Your Amortization Schedule
Look at year 5 and year 10 in your schedule — these are the decision points. If you plan to sell or refinance before year 10, you've barely touched the principal. In that scenario, making extra payments is less valuable because you won't be around long enough to capture the compound savings. On the other hand, if you plan to stay for 20+ years, paying an extra $100–$300/month from day one is one of the most reliable risk-free returns available.
One common mistake: making extra payments without specifying they should go to principal. Always mark extra payments as "principal only" when submitting to your lender. Otherwise, some servicers apply the extra amount to future scheduled payments instead — which doesn't reduce your balance.
Frequently Asked Questions About Amortization
What is an amortization schedule?
An amortization schedule is a complete table of every loan payment over the full loan term, showing how each payment is split between principal repayment and interest. It also shows the remaining loan balance after each payment.
Why do I pay so much interest at the beginning?
Interest is calculated as a percentage of your outstanding balance. At the start of a 30-year loan, your balance is at its highest, so the interest charge is largest. As you pay down principal, the balance falls and interest charges shrink — but this happens slowly at first.
Does making one extra payment per year really help?
Yes. On a $360,000 loan at 7%, one extra payment of $2,395 per year shortens the loan by about 4 years and saves roughly $63,000 in interest. The effect compounds because every extra principal payment reduces the base on which all future interest is calculated.
What is the difference between amortization and depreciation?
Amortization applies to loans — it describes paying down debt over time. Depreciation applies to assets — it describes spreading the cost of a physical asset (like equipment) over its useful life. Both distribute costs over time, but they apply to opposite sides of a balance sheet.
Can I get my amortization schedule from my lender?
Yes — your lender is required to provide it upon request. Your loan disclosure documents should also include a payment schedule. However, the schedule won't show the impact of extra payments, which is why calculators like this one are useful.
What happens to my amortization schedule if I refinance?
Refinancing resets your amortization schedule entirely. You start a new loan with a new principal balance. If you have 22 years left on your current mortgage and refinance into a new 30-year loan, your payoff date moves further out even if the rate is lower.
What is a 15-year vs 30-year amortization comparison?
A 15-year loan on $320,000 at 6.3% costs $2,767/month but only $178,060 in total interest. The same loan at 6.8% for 30 years costs $2,091/month but $433,760 in total interest. The 15-year saves $255,700 but requires $676/month more.
Does the amortization schedule change if rates change?
Only on adjustable-rate mortgages (ARMs). Fixed-rate loans have the same schedule from day one. On an ARM, when the rate adjusts, your remaining balance is recalculated with the new rate and the schedule resets for the remaining term.
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