What Is a Loan Calculator?
A loan calculator is a free online tool that estimates your monthly payment on a fixed-rate installment loan — including personal loans, auto loans, and other consumer loans — based on the amount you borrow, your interest rate, and how many years you'll take to repay it.
Enter your loan amount, annual interest rate, and term above, and the calculator instantly shows your monthly payment, total interest, and a year-by-year amortization breakdown.
How to Use the Loan Calculator
- Enter the total amount you plan to borrow.
- Enter the annual interest rate (APR) offered by your lender.
- Enter the loan term in years.
- Add any origination fees if your lender charges them.
- Review your monthly payment, total interest, and full repayment schedule below.
Loan Payment Formula
Fixed-rate loans use the standard amortization formula:
How the Calculation Works
The annual interest rate is first converted to a monthly rate by dividing by 12. Each monthly payment is split between interest (calculated on the remaining balance) and principal (which reduces the balance). Early payments are interest-heavy; later payments are mostly principal, which is why the amortization table shows the interest share shrinking every year.
Worked Example
Loan amount: $20,000
Interest rate: 7.5% APR
Term: 5 years (60 months)
Monthly rate: 7.5% ÷ 12 = 0.625%
Result: monthly payment of roughly $401, with total interest of about $4,038 over the life of the loan.
Understanding Your Results
Monthly Payment is the fixed amount you'll pay every month for the life of the loan. Total Interest is the extra cost of borrowing on top of your principal — the price you pay for the convenience of spreading repayment over time. Total Paid is your principal plus total interest, the true cost of the loan.
Factors That Affect Your Loan Payment
- Credit score: Higher scores typically qualify for lower interest rates.
- Loan term: Longer terms lower your monthly payment but increase total interest paid.
- Loan type: Secured loans (backed by collateral) usually carry lower rates than unsecured loans.
- Lender fees: Origination fees add to your effective borrowing cost even though they aren't part of the interest rate.
Tips for Getting a Better Loan Rate
- Compare offers from at least 3–4 lenders before committing.
- Check your credit report for errors before applying.
- Consider a shorter term if you can afford the higher payment — you'll pay far less interest overall.
- Ask lenders whether the rate quoted is APR (which includes fees) or a simple interest rate.
Common Mistakes to Avoid
- Confusing the interest rate with APR — APR includes fees and is the more accurate cost comparison.
- Choosing the longest term just to get the lowest monthly payment without checking total interest cost.
- Ignoring prepayment penalties some lenders charge for paying off a loan early.
- Not accounting for origination fees when comparing loan offers.
Frequently Asked Questions
A fixed-rate loan payment is calculated using the loan amount, the monthly interest rate (annual rate divided by 12), and the total number of monthly payments, applied to the standard amortization formula shown above.
The interest rate is the cost of borrowing the principal. APR (annual percentage rate) includes the interest rate plus most lender fees, giving you a more complete picture of the loan's true annual cost.
No — a longer term lowers your monthly payment but increases the total interest you pay over the life of the loan, since interest accrues for more months.
Many personal and auto loans allow early payoff without penalty, which reduces total interest. Some loans do carry a prepayment penalty, so check your loan agreement first.
Lenders typically reserve their best rates for borrowers with credit scores above 700, though options exist across most credit ranges at higher rates.
It uses the standard amortization formula used by banks and lenders for fixed-rate installment loans. Your actual offer may vary slightly based on fees, rounding, and how your lender compounds interest.
This calculator works well for personal loans, auto loans, and any other fixed-rate installment loan with equal monthly payments. For mortgages, use our dedicated Mortgage Calculator, which accounts for taxes and insurance.