What will your loan cost per month — and how much can you save with a shorter term or extra payments?

Loan payments are calculated using the standard amortization formula, which spreads the principal and interest evenly across all monthly payments. Each payment includes two parts: interest on the remaining balance and a portion that reduces the principal. Early in the loan, most of your payment goes to interest; by the end, most goes to principal. The formula ensures the loan is fully paid off by the last scheduled payment.

The interest rate is the annual cost of borrowing the principal, expressed as a percentage. The APR (Annual Percentage Rate) includes the interest rate plus any mandatory fees like origination charges, spread over the life of the loan. The APR is always equal to or higher than the interest rate. When comparing loan offers from different lenders, APR gives a more complete picture of the true cost because it factors in fees that the interest rate alone does not capture.

Your credit score is the single biggest factor in the interest rate a lender offers you. Borrowers with excellent credit (750+) typically qualify for rates 3–8 percentage points lower than borrowers with fair credit (580–669). On a $25,000 five-year loan, the difference between a 5% rate and a 12% rate is roughly $5,000 in total interest. Improving your credit score by even 50 points before applying can save you hundreds or thousands of dollars over the loan term.

A fixed rate stays the same for the entire loan term, so your monthly payment never changes. A variable rate starts lower but can increase or decrease based on market conditions. For loans under 5 years, variable rates are often safe because there is less time for rates to rise significantly. For longer terms (5–7 years), a fixed rate provides certainty and protects you from rising rates. If you plan to pay off the loan early, a variable rate with a low starting point may cost less overall.

Some lenders charge prepayment penalties — fees for paying off the loan before the scheduled end date. This is more common with auto loans and certain personal loans than with student loans. Federal student loans never have prepayment penalties. Before making extra payments, check your loan agreement for a prepayment clause. If a penalty exists, calculate whether the interest savings from early payoff still exceed the penalty. Many lenders have moved away from prepayment penalties, especially for personal loans.