Fixed vs Variable Student Loan Refinance Rates
This calculator places a fixed-rate refinance offer next to a variable-rate offer so you can see how total cost diverges over your repayment period. Enter your balance, both rate offers, and a scenario where the variable rises to a level you choose. The fixed rate gives certainty; the variable offers a lower entry point with exposure to increases.
In this scenario you save
Difference between the two
by taking the variable rate — even after it rises to in .
by taking the fixed rate. The rise you modelled wipes out the variable loan's head start.
The two land within a dollar of each other on these numbers.
- Over FixedVariable
- Payment at the start
- Payment after the rise
- Interest paid
- Total paid
The variable loan stops being the cheaper one once the rate climbs past at that same month.
The variable loan is modelled the way lenders handle a rate change: the remaining balance is re-amortised over the remaining term at the new rate, so the payment jumps by . Real variable rates move more than once and have their own caps — check the loan agreement.
How Refinance Variable Rates Are Set
Private student loan refinance lenders typically price variable rates as SOFR (the Secured Overnight Financing Rate) plus a margin that reflects your credit profile. When SOFR moves, your rate adjusts on the schedule specified in your loan agreement, often monthly or quarterly. Most lenders impose a lifetime rate cap, but that cap can sit several points above the starting rate.
The difference between a refinance variable rate and the variable rate on an original private student loan is the margin. Refinancing resets the margin based on your current credit score, income, and debt-to-income ratio. If your credit has improved since you first borrowed, the new margin may be lower, giving you a starting rate well below your original loan. The calculator lets you test what happens if the benchmark rate climbs after you lock in that lower starting point. Enter a realistic peak scenario to see whether the eventual payment increase erodes the initial savings.
Choosing Between the Starting Discount and Long-Term Certainty
Variable rates look cheaper at signing because lenders price the risk of rate movement into the fixed-rate offer. If rates hold steady or decline during your repayment period, the variable borrower keeps the discount and pays less overall. If rates rise, the variable borrower's advantage narrows and can invert entirely.
The key question is how long you plan to hold the loan. Borrowers who intend to repay within three to five years face limited rate-rise exposure, and the variable discount often wins. Those on seven-year or longer terms face more uncertainty. The calculator quantifies the crossover: it shows the month at which the variable scenario's cumulative cost exceeds the fixed scenario's cumulative cost. Refinancing federal loans into a private loan is irreversible and removes access to IDR, PSLF, forbearance, and disability discharge. For a deeper look at the crossover math, see the fixed-vs-variable break-even calculator.
All rates shown are illustrative. Variable rates depend on SOFR plus lender margin and are subject to lender terms. This is not a rate offer.
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Related student loan calculators
- Should I Refinance My Variable Rate Student Loan?
- Fixed vs Variable Student Loan Refinance Break Even
Sources
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Sources: SOFR benchmark (newyorkfed.org); credible.com 2026 refinance rate-band survey; standard amortization math.
- Federal Direct Consolidation Loan interest rate — the weighted average of the loans being consolidated, rounded up to the nearest one-eighth of one percent (Federal Student Aid, studentaid.gov, Loan Consolidation).
- Amortisation, daily interest accrual and payoff arithmetic — standard loan mathematics; every figure on this page is computed from the numbers you enter.