Amortization Calculator
An amortization calculator helps you understand how loan payments are applied over time. Whether you’re planning a mortgage, auto loan, or personal loan, this tool shows your monthly payment, total interest, and how your balance shrinks with each payment.
How This Calculator Works
Simply enter your loan details—amount, term, interest rate, and any extra payments—and the calculator instantly generates:
- Monthly payment amount
- Complete amortization schedule
- Pie chart showing principal vs. interest
- Year-by-year breakdown of balances and payments
Optional features let you model extra monthly, yearly, or one-time payments to see how much faster you can pay off your loan.
Formula Explanation
The calculator uses the standard amortization formula to compute your fixed monthly payment:
M = P × [r(1+r)^n] / [(1+r)^n − 1]
- M = monthly payment
- P = principal loan amount
- r = monthly interest rate (annual rate ÷ 12)
- n = total number of payments (years × 12)
Each payment is split between interest (based on the remaining balance) and principal reduction. Over time, more of your payment goes toward principal and less toward interest.
Step-by-Step Example
Example: A $200,000 loan at 6% annual interest over 15 years (180 months).
- Monthly payment: $1,687.71
- Total payments: $303,788.46
- Total interest: $103,788.46
- First month: $1,000 interest, $687.71 principal
- Last month: ~$8.40 interest, ~$1,679.32 principal
Benefits of Using This Calculator
Understand the true cost of borrowing and plan your payments strategically.
- See exactly how extra payments reduce your loan term
- Compare annual vs. monthly amortization schedules
- Visualize interest vs. principal with pie charts and graphs
- Save and reuse your calculations for future reference
Common Mistakes to Avoid
Avoid these pitfalls when planning your loan repayment:
- Forgetting to include extra payments in your plan
- Assuming the interest rate won’t change (if it’s variable)
- Overlooking fees that may not appear in amortization schedules
- Using this tool for non-amortizing loans like credit cards or interest-only plans
Frequently Asked Questions
1. What is an amortization schedule?
It’s a table showing each payment’s breakdown into interest and principal, along with your remaining balance after each payment.
2. Can I use this for an adjustable-rate loan?
This calculator is designed for fixed-rate loans. For adjustable rates, your payments will change over time and require recalculation.
3. How do extra payments affect my loan?
Extra payments reduce your principal faster, which lowers the total interest you pay and can shorten your loan term significantly.
4. Why does the interest portion decrease over time?
Interest is calculated on the remaining balance. As you pay down principal, less interest accrues, so more of your payment goes toward reducing the principal.
5. Is this calculator suitable for business loans?
Yes, it works for any amortizing loan, including business loans, equipment financing, and personal loans with fixed terms.
Final Thoughts
An amortization calculator is a powerful tool for making informed borrowing decisions. By visualizing how your payments are applied, you can save money on interest, pay off debt faster, and gain greater control over your financial future.