Loan Interest & Amortization Calculator
Calculate monthly payments and generate a full amortization schedule. Features an "Extra Payment" analyzer to see interest savings.
Monthly Payment
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Total Interest
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Amortization Schedule
| # | Payment | Principal | Interest | Balance |
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About
Borrowers often underestimate the total cost of a loan because they focus solely on the monthly payment. This tool dissects the payment structure, separating principal from interest over the life of the loan. The most powerful feature is the Extra Payment analyzer. By adding a small amount to the principal every month, the compounding nature of interest works in reverse, drastically reducing the term and total cost. The generated schedule provides a month-by-month roadmap to becoming debt-free.
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Formulas
The standard annuity formula calculates the fixed monthly payment required to pay off the loan.
A = P × r(1+r)n(1+r)n−1
Reference Data
| Variable | Description | Standard Formula |
|---|---|---|
| Principal | Loan Amount ($) | P |
| Rate | Annual Interest Rate | r / 12 |
| Term | Number of Payments | n |
| Payment | Monthly Installment | PMT(P, r, n) |
Frequently Asked Questions
Amortization is the process of spreading a loan into a series of fixed payments. While the payment amount stays the same, the portion covering interest decreases while the principal portion increases over time.
Extra payments go 100% towards the principal balance (usually). This reduces the balance on which next month's interest is calculated, creating a snowball effect that shortens the loan term.
This tool generates a detailed table on-screen which you can print or copy-paste into Excel to track your progress manually.
Yes. Most fixed-rate mortgages, auto loans, and personal loans use this standard amortization math.