Loan Payment & Amortization Calculator
Calculate monthly loan payments, total interest, and payoff time (USD)
Loan calculator FAQs
What’s the difference between APR and interest rate?
APR is the annual percentage rate quoted by lenders. It reflects the yearly cost of borrowing and is what this calculator uses to build your payment schedule. Some marketing materials show a nominal rate without fees; APR is usually the better number to compare offers.
Do extra monthly payments really make a difference?
Yes. Every extra dollar paid on top of the required amount goes straight to principal after interest for that month. That shrinks the remaining balance faster, which reduces future interest and often removes months or years from the payoff timeline.
Can I use this for mortgages, car loans, and personal loans?
This page works for most fixed-rate, fully amortizing loans where you make one monthly payment until the balance reaches zero. Mortgages with escrow, adjustable-rate loans, and products with balloon payments or fees will differ in practice from this simplified model.
Does the calculator include taxes, insurance, or fees?
No. Results focus on principal and interest only so you can compare offers cleanly. Property taxes, insurance, origination fees, prepayment penalties, and other charges still need to be checked in your loan paperwork or with your lender.
Is this financial advice?
This page is an educational estimate only and does not replace advice from a licensed professional. Always confirm key numbers against official loan disclosures and statements before making big decisions.
How to use this loan payment & amortization calculator
1. Turn a loan offer into clear monthly numbers
The calculator takes the three inputs that matter most—loan amount, APR, and term in years—and converts them into a concrete monthly payment in USD. Instead of guessing whether “6.99% for 5 years” is affordable, you see the exact amount you would pay each month and how long it will take to clear the balance.
2. Compare offers on total interest, not just payment size
Lower monthly payments can be tempting, but they often come from stretching the term, which increases total interest. The results box highlights both the payment and the full cost: total interest over the life of the loan and the combined principal-plus-interest total. That makes it easy to see whether you are trading a smaller monthly bite for a much higher long-term price.
3. See the impact of extra monthly payments
In the extra payment field, enter an amount you could realistically add on top of the required payment— maybe $25, $50, or $100. The calculator recomputes the amortization schedule, showing the new payoff time, how much interest you save, and how many months you shave off the loan. The effect is often bigger than people expect, especially on longer terms.
4. Use the start month to visualize your payoff date
The start month is optional but useful. Set it to the month your first payment is due. The summary then estimates a payoff month based on the number of periods in the schedule, giving you a simple sentence like “Paid off around June 2030” that you can paste into a budget, email, or notes app.
5. Copy the summary into your own planning tools
When you tap Copy summary, the tool generates a compact breakdown: principal, APR, term, monthly payment, total interest, total cost, and the effect of any extra payment. Paste that into a spreadsheet, compare multiple offers side by side, or drop it into a message when you discuss options with a partner or advisor.
6. Treat this as a clean baseline, then layer in real-world details
The math here focuses on principal and interest so you can compare different loans on an even playing field. Actual repayments can include taxes, insurance, rate changes, or fees. Use this page to build intuition and shortlists, then confirm the final numbers against official disclosures, especially if prepayment penalties or adjustable rates are involved.
How the loan amortization math is approximated
Let P be the principal (loan amount in USD), a the APR as a decimal (for example, 6.99% → 0.0699), and y the term in years. The number of planned monthly payments is n = 12y. The monthly rate is r = a/12. For a positive rate, the standard fixed-payment formula gives the monthly payment:
payment = P × r / (1 − (1 + r)−n). If APR is zero, the payment simplifies to P / n.
Each month, interest is balance × r and the rest of the payment reduces principal. When you enter an extra monthly payment, that extra amount is added to the principal portion after interest, shrinking the balance more quickly and reducing both payoff time and total interest. We build the schedule month by month until the balance reaches zero, summing all interest and payments along the way.
The calculator rounds displayed amounts to cents, so the final payment in the schedule may be slightly smaller than the regular monthly amount. This keeps the model intuitive while staying close to how many lenders generate their amortization tables.