📊 Loan Interest Calculator
Calculate your monthly payments, total interest, and total loan cost. See a complete amortization schedule showing exactly how each payment is applied to principal and interest over the life of your loan. Perfect for mortgages, auto loans, personal loans, and more.
What Is a Loan Interest Calculator?
A loan interest calculator helps you understand the true cost of borrowing. It calculates your monthly payment, total interest paid over the life of the loan, and the total cost of the loan including principal and interest.
Loans use simple interest amortization. Each monthly payment is divided between interest charges and principal reduction. Early in the loan, a larger portion goes toward interest; later, more goes toward principal because interest is calculated on the outstanding balance, which decreases over time.
How Does the Loan Interest Calculator Work?
The calculator uses the standard loan payment formula:
Where:
- M = Monthly payment
- P = Principal (loan amount minus down payment)
- r = Monthly interest rate (Annual rate ÷ 12)
- n = Total number of payments (loan term in months)
Why Use This Loan Interest Calculator?
- Full Amortization: See exactly how each payment is split between principal and interest.
- Extra Payments: See how paying extra each month can save you thousands in interest and shorten your loan term.
- Visual Charts: Understand the cost breakdown with a pie chart and balance trajectory.
- Detailed Breakdown: View the complete calculation step by step.
- Free & Private: No registration, no data storage , all calculations run in your browser.
❓ Loan Interest Calculator FAQ
What is the difference between principal and interest?
Principal is the amount you borrowed. Interest is the cost of borrowing that money, calculated as a percentage of the remaining balance. Each payment covers both principal and interest.
What is an amortization schedule?
An amortization schedule shows each payment's breakdown between principal and interest, along with the remaining balance. It helps you understand how your loan is paid off over time.
How does paying extra each month help?
When you pay extra each month, the extra amount is applied directly to the principal balance. This reduces your total interest paid and can shorten your loan term significantly.
What is a good interest rate for a personal loan?
Good rates vary by credit score. With excellent credit (750+), rates are typically 6-10%. With good credit (700+), expect 8-14%. With fair credit (650+), rates may be 14-20%.
What is the difference between APR and interest rate?
APR (Annual Percentage Rate) includes interest plus fees. The interest rate is the base cost of borrowing. Always compare APR when shopping for loans.
What is the formula for calculating loan payments?
The formula is M = P × [r(1+r)^n] / [(1+r)^n − 1], where M is the monthly payment, P is the principal, r is the monthly interest rate, and n is the number of payments.
How does the down payment affect my loan?
A larger down payment reduces your loan amount, which lowers your monthly payment and saves you thousands in interest over the life of the loan.
Why does a shorter loan term save money?
While shorter loan terms have higher monthly payments, they save significant interest. For example, on a $25,000 loan at 6.5%, a 48-month term saves $1,847 in interest compared to a 72-month term.
How accurate is this calculator?
This calculator provides accurate results based on the standard loan amortization formula. Use it as a planning tool and consult a financial professional for specific borrowing decisions.
Is this calculator free to use?
Yes, this calculator is completely free to use. No registration or personal data storage is required. All calculations are performed in your browser.