🏦 Loan Calculator
Calculate your monthly payments, total interest, and view a full amortization schedule. Includes extra payment simulator.
Principal vs Interest Breakdown
💰 Extra Payment Simulator
📋 Amortization Schedule
| Month | Payment | Principal | Interest | Balance |
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📋 When to Use the Loan & Mortgage Calculator
Homebuyers compare mortgage offers by entering different rates and terms to see monthly payments and total interest. Car buyers run loan scenarios for different amounts and durations. Anyone with existing debt uses the Extra Payment Simulator to test how adding even \$50–100/month shaves years off the payoff date and saves thousands in interest. The full amortization schedule shows exactly how each payment splits between principal and interest. ⚠️ This calculator uses the standard PMT formula with fixed-rate assumptions — actual loans may include fees, variable rates, or prepayment penalties not reflected here. This is not financial advice.
⚙️ How the Loan & Mortgage Calculator Works
The monthly payment is computed using the standard amortization PMT formula: M = P × [r(1+r)^n] / [(1+r)^n − 1], where P = principal, r = monthly interest rate (annual rate ÷ 12), and n = total months (years × 12). The amortization schedule iterates month by month: interestPart = balance × r, principalPart = payment − interestPart, then subtracts from the balance. For long loans (>48 months), only the first and last 12 months are shown with a collapsed summary in between. Extra payments accelerate payoff by reducing principal faster — the simulator recalculates the shortened timeline and total interest saved. A Chart.js pie chart visualizes the principal-vs-interest split.
How to Use the Loan Calculator
- Enter your loan amount — the total principal you're borrowing (e.g., 200,000 for a mortgage or 25,000 for a car loan).
- Set the interest rate and term — use the annual interest rate (e.g., 6.5 for 6.5%) and loan term in years. The calculator computes your monthly payment using the PMT formula.
- Add extra payments (optional) — enter an extra monthly amount to see how much faster you can pay off the loan and how much interest you'll save.
- Review the amortization schedule — scroll down to see month-by-month breakdown of principal vs. interest, plus a pie chart of your total loan cost.
Frequently Asked Questions
How is the monthly payment calculated?
The calculator uses the standard PMT formula: M = P × [r(1+r)^n] / [(1+r)^n − 1], where P = principal, r = monthly interest rate (annual rate / 12), and n = total number of payments (years × 12).
How much can extra payments save me?
Even small extra payments make a big difference. For example, adding $100/month to a $200,000 30-year mortgage at 6.5% saves over $50,000 in interest and pays off the loan ~7 years early. Enter your numbers to see your specific savings.
What's the difference between principal and interest?
Principal is the original loan amount you borrowed. Interest is the cost of borrowing, calculated as a percentage of the remaining balance. Early in the loan, most of your payment goes to interest; later, more goes to principal.
Why does the amortization schedule show fewer months with extra payments?
Extra payments go directly toward reducing the principal balance. A lower balance means less interest accrues each month, so more of your regular payment goes to principal — accelerating payoff. The schedule adjusts automatically.