Amortization Calculator
Calculate a fixed monthly loan payment, total interest, payoff time, and an amortization schedule.
Runs in this browser. No upload by this tool. Copy/download/export locally.
Loan
Payment setup
Enter the fixed-rate loan terms. Extra payment is optional.
Monthly payments only. Taxes, fees, insurance, changing rates, and lender-specific rules are not included.
Result
Result
—Export result
Copy a readable summary or download the current result as a local file.
Create a valid result to enable local exports.
How Amortization Calculator works
Use the calculator first. The sections below explain the inputs, worked examples, method, outputs, and limits.
How to use
- Enter the loan amount.
- Enter the annual fixed interest rate and term in years.
- Optionally add an extra monthly principal payment.
- Review the payment, total interest, payoff time, and schedule.
- Copy the summary or export the current result locally.
Worked examples
Standard fixed-rate example
A $250,000 loan at 6.5% for 30 years produces a modeled principal-and-interest payment of about $1,580.17 per month.
Zero-interest example
A $12,000 balance at 0% for 1 year produces twelve scheduled payments of $1,000.
Extra-payment effect
Adding extra principal each month can reduce both the modeled payoff time and total interest.
Last-payment behavior
If the normal payment would exceed the remaining balance, the final payment is reduced to close the balance.
Result reference
Monthly payment
The scheduled principal-and-interest payment before any optional extra principal payment.
Total interest
The modeled interest paid across the generated schedule.
Payoff time
The number of monthly payments required after applying any extra payment.
Remaining balance
The balance after each payment in the amortization schedule.
FAQ
What is an amortization schedule?
It is a payment-by-payment breakdown showing how each payment is split between interest and principal and how the remaining balance changes.
How is the monthly payment calculated?
For a fixed-rate loan, the calculator uses the standard level-payment amortization formula. A zero-interest loan is handled separately as principal divided by the number of payments.
Does an extra monthly payment reduce interest?
Yes in this model. Extra payment is applied to principal each month, which can shorten the payoff period and reduce future interest.
Does this include taxes or insurance?
No. It models principal and interest only, plus an optional extra principal payment.
Can I use a 0% interest rate?
Yes. The calculator divides principal evenly across the selected number of monthly payments.
Why can the last payment be smaller?
The final payment is capped at the remaining balance plus that month's interest so the schedule does not overpay the loan.
Is this a lender quote?
No. It is a planning calculation based only on the values you enter.
What does total interest mean?
It is the sum of modeled interest charges across the generated schedule.
Can I export the full schedule?
Yes. CSV and JSON preserve the full schedule. The on-page, Word, and print views may show a shorter report-friendly excerpt.
Are results saved?
No. This tool does not save the loan values or schedule after the page is closed or cleared.
Method & limitations
Formula
For monthly rate i and n payments, payment = P × i ÷ (1 − (1+i)^−n). At 0%, payment = P ÷ n.
Schedule
Each month calculates interest on the opening balance, then applies the scheduled principal and optional extra principal.
Rounding
Internal arithmetic uses JavaScript floating-point values; displayed currency is rounded to cents.
Scope
This is a deterministic principal-and-interest planning model, not a quote or underwriting decision.
Review loan documents and lender disclosures before making financial decisions. This tool does not model taxes, insurance, fees, variable rates, or lender-specific payment rules.