Amortization CalculatorFree online financial calculator — instant results, no sign-up
See how each year of payments splits between interest and principal.
Estimates only, based on the inputs and assumptions shown. This is not financial, investment, tax, or legal advice. Prices, rates and local rules may change; crypto scenarios do not predict returns. Confirm important decisions with a qualified professional.
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How the result changes with loan amount
Each row below was calculated with this tool, keeping every other input at its default and changing only loan amount from half to one and a half times the default value. Use it to see how sensitive the answer is before you enter your own numbers.
| Loan amount ($) | Monthly payment | Total of payments | Total interest |
|---|---|---|---|
| 100,000 | $843.86 | $151,894.23 | $51,894.23 |
| 150,000 | $1,265.79 | $227,841.34 | $77,841.34 |
| 200,000 (default) | $1,687.71 | $303,788.46 | $103,788.46 |
| 250,000 | $2,109.64 | $379,735.57 | $129,735.57 |
| 300,000 | $2,531.57 | $455,682.69 | $155,682.69 |
About the Amortization Calculator
This amortization calculator computes the fixed monthly payment for a fully amortizing loan and displays an annual breakdown of how each year's payments divide between principal and interest. Borrowers, homeowners, and financial planners use it to observe how equity builds and remaining loan balance declines over time.
- Loan amount
- The total initial principal borrowed, measured in dollars (typically $1,000 to $2,000,000+).
- Interest rate
- The fixed annual nominal interest rate as a percentage (sensibly 0.1% to 25%).
- Term
- The length of the loan payoff period in full years (commonly 5 to 30 years).
Formula and method
Monthly Payment: M = P × [r(1 + r)^n] / [(1 + r)^n − 1] Monthly Interest: I_k = B_(k-1) × r Monthly Principal: C_k = M − I_k Remaining Balance: B_k = B_(k-1) − C_k
- MFixed monthly payment amount
- PInitial principal loan amount
- rPeriodic monthly interest rate (annual interest rate / 100 / 12)
- nTotal number of monthly payment periods (term in years × 12)
- B_kEnding loan balance at month k (with B_0 equal to P)
- I_kInterest paid in month k
- C_kPrincipal paid in month k
The calculator converts the annual rate to a monthly rate and computes the fixed monthly payment using the standard annuity formula. It then iterates through every month of the loan term to allocate payments toward accrued interest and loan balance reduction, finally grouping each consecutive 12 months into yearly interest, principal, and ending balance figures.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Loan amount200000 $
- Interest rate6 %
- Term15 years
Results
- Monthly payment$1,687.71
- Total of payments$303,788.46
- Total interest$103,788.46
- Year 1Interest $11,769.23 · Principal $8,483.33 · Balance $191,516.67
- Year 2Interest $11,246.00 · Principal $9,006.57 · Balance $182,510.10
- Year 3Interest $10,690.49 · Principal $9,562.07 · Balance $172,948.02
How to use the Amortization Calculator
- 1Convert the loan term to months (years × 12) and the annual interest rate to a decimal monthly rate (rate / 1200).
- 2Calculate the fixed monthly payment using the standard loan amortization formula.
- 3For each month, compute interest owed on the remaining balance, deduct that from the monthly payment to find principal paid, and subtract the principal from the balance.
- 4Sum each 12-month block to display total annual interest paid, total annual principal paid, and the end-of-year remaining balance.
Reading your result
Early annual entries show that the majority of each payment goes toward interest charges, reducing the balance slowly. As the outstanding balance declines in later years, the monthly interest portion shrinks, causing principal reduction and equity accumulation to accelerate toward complete payoff at year zero.
Limitations
The model assumes a fixed interest rate and standard monthly compounding for the entire loan life. It does not account for variable interest rates, prepayments, extra principal payments, escrow charges (such as property taxes or home insurance), origination fees, or loan penalties.
Common questions
Why is the interest portion so high during the first few years?+
Interest is assessed on the outstanding loan balance each month. Because the balance is highest at the beginning of the term, interest accounts for a substantial majority of the early monthly payments.
How does choosing a shorter loan term change amortization?+
A shorter loan term requires higher monthly payments, but pays down the principal balance much faster, resulting in significantly lower cumulative interest charges over the life of the loan.
Does this schedule include property taxes or private mortgage insurance (PMI)?+
No. This schedule reflects only principal and interest (P&I). Actual monthly housing payments often include escrowed property taxes, homeowners insurance, and mortgage insurance.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
Further reading
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Results are estimates for informational purposes and are not financial, medical or legal advice.