Amortization Schedule
See how your loan payments split between principal and interest
How to Use This Tool
Enter your loan details: the total borrowed amount, annual interest rate (as a percentage), loan term in years, and payment frequency (monthly, bi-weekly, or weekly). Click "Calculate Schedule" to generate a complete amortization table. The summary shows your fixed periodic payment, total amount you'll pay over the life of the loan, and total interest costs. The table breaks down each payment into principal and interest portions and tracks your remaining balance after each payment.
Formula and Logic
The calculator uses the standard loan amortization formula: Payment = P × r × (1+r)^n / [(1+r)^n – 1], where P is the principal loan amount, r is the periodic interest rate (annual rate divided by payments per year), and n is the total number of payments. For each period, interest is calculated as the current balance × periodic rate, and the remainder of the fixed payment reduces the principal. The schedule assumes fixed payments throughout the loan term and does not account for rate changes, fees, or skipped payments.
Practical Notes
Interest Rate Effects: A higher interest rate dramatically increases total interest paid. For example, on a $300,000 30-year loan, 4% interest yields ~$215,000 total interest, while 7% yields ~$418,000—nearly double. Even small rate differences matter over long terms.
Compounding Frequency: More frequent payments (bi-weekly vs. monthly) can reduce total interest because you're paying down principal faster and making 13 monthly payments per year. However, lenders may charge fees for bi-weekly programs, and not all loans allow this without penalty.
Tax Implications: Mortgage interest may be tax-deductible if you itemize deductions, effectively reducing your net interest cost. Consult a tax advisor about your specific situation. This calculator shows pre-tax interest costs.
Budgeting Habits: Use this tool to compare loan offers, decide between 15-year vs. 30-year terms, or plan extra principal payments. Making just one extra payment per year can shorten a 30-year mortgage by several years and save tens of thousands in interest.
Why This Tool Is Useful
Visualizing your amortization schedule reveals how early payments are mostly interest while later payments are mostly principal. This knowledge empowers you to make strategic decisions: refinancing when rates drop, making extra payments when possible, and understanding the true cost of extending loan terms. For financial planners, this tool helps clients see the long-term impact of debt and motivates aggressive repayment strategies. It also aids in comparing loan offers by showing total interest costs side-by-side.
Frequently Asked Questions
Can I use this for an adjustable-rate mortgage (ARM)?
No. This calculator assumes a fixed interest rate for the entire loan term. ARMs have rates that change periodically, which would require recalculating the schedule at each adjustment date. For ARMs, use a specialized ARM calculator that models rate changes based on index and margin.
Why does my total interest exceed the loan amount?
This is common with long-term loans. For example, a $200,000 loan at 6% over 30 years yields ~$231,000 in total interest—more than the principal. This happens because interest accrues on the outstanding balance over many years. Shorter terms (e.g., 15 years) or lower rates drastically reduce this ratio.
How do extra principal payments affect my schedule?
Extra payments directly reduce the principal balance, which reduces the interest charged in subsequent periods. This shortens the loan term and saves interest. To model this, run the calculator with the original terms, then manually adjust the balance after your extra payment and recalculate the remaining schedule. Some lenders apply extra payments to principal automatically; confirm their policy.
Additional Guidance
When entering loan terms, use the exact figures from your loan agreement. If your loan includes upfront fees (origination, documentation) that are financed into the loan, include those in the loan amount. For loans with balloon payments (large final payment), this calculator is not suitable—it assumes the loan is fully amortized with equal payments. Always verify your lender's amortization schedule, as some use slightly different day-count conventions (e.g., 360-day year vs. actual/365). For business or commercial loans, consult your lender about specific amortization methods (straight-line, declining balance, etc.).