Soft pull vs hard pull
The key distinction is the type of credit check. When you prequalify — whether on a single lender's site or through a rate-comparison marketplace — the lender runs a soft credit pull, which lets you see estimated rates without affecting your score. You can compare prequalified offers from several lenders this way at no risk. A hard credit pull happens only later, when you choose a lender and submit a formal application. That hard inquiry is what can move your score, and it is entirely within your control: nothing dings your credit until you decide to apply.
How much it actually moves your score
A single hard inquiry typically lowers a score by only a few points, and the effect usually fades within a few months. Credit-scoring models also recognize rate shopping: if you apply with multiple student-loan lenders within a short window (often 14–45 days, depending on the model), the inquiries are generally treated as one for scoring purposes — so comparing a few formal offers in a tight timeframe does not multiply the impact. The temporary dip is small relative to the potential benefit of a lower interest rate.
Why it can help your credit over time
Beyond the brief inquiry dip, refinancing can be neutral or positive for your credit in the long run. Replacing several loan payments with a single, on-time payment reduces the chance of a missed due date, and payment history is the largest factor in most credit scores. Lowering your interest rate can also help you pay the balance down faster. The closed original loans may stay on your report for years and continue to support your credit-age, depending on the bureau. The one real risk to your credit is the obvious one: if a lower payment tempts you to take on new debt, or you miss payments on the new loan, that will hurt — refinancing only helps if you keep paying on schedule.
The non-credit risk that matters more
For federal borrowers, the credit-score question is the small one. The bigger issue is that refinancing federal loans into a private loan permanently forfeits federal protections — income-driven repayment, forgiveness, and federal hardship options — and that cannot be undone. So weigh the trade-off that actually matters: a few temporary credit points is minor, but losing federal benefits is permanent. Confirm what you would give up at studentaid.gov before refinancing any federal loan.