Highest Interest or Smallest Student Loan First?
Paying the highest-interest loan first (the avalanche method) saves the most in total interest. Paying the smallest balance first (the snowball method) delivers quicker wins that keep you motivated. The right choice depends on the rate spread between your loans. Enter your balances and rates above to compare both strategies side by side.
New monthly payment
You pay today, so that is a month back in your pocket.
That is more than the you pay today — the shorter term costs more each month but clears the debt sooner.
- Over the whole termStay putRefinance
- Monthly payment
- Interest you pay
- Debt-free
- Total paid
No switching cost to earn back — you are ahead from the first payment, by over the life of the loan.
You earn the switching cost back after payments — around .
At these numbers the new loan never pays for itself: the monthly payment does not fall.
Careful — the lower payment comes from a longer term. Over the full term this deal costs more than staying put.
Both loans are modelled as fixed-rate, fully amortising, with no missed months. A refinance replaces your loan with a brand-new private loan — see what that costs you below.
Rate drop
Monthly change
Interest saved
Lifetime saving
What you give up when federal loans go private
- Income-driven repayment. A private lender sets one payment; it does not fall when your income does.
- Federal forgiveness programmes, including Public Service Loan Forgiveness and any income-driven forgiveness after the full repayment term.
- Federal discharge on death or total and permanent disability — private lenders decide their own policy.
- Federal deferment and forbearance rights, and the federal rehabilitation route out of default.
- The decision is one-way. Once a federal loan is refinanced privately, it cannot be turned back into a federal loan.
Refinancing private loans into a cheaper private loan gives up none of this — it is federal balances that carry the risk.
When Avalanche Wins and When Snowball Makes Sense
The avalanche approach directs every spare dollar at the loan with the highest interest rate while you pay minimums on the rest. Once that loan is gone, you roll its payment into the next-highest rate. Mathematically, this always produces the lowest total interest cost. For a borrower with four loans whose rates range from 4% to 8%, the interest gap between the two methods can amount to hundreds or even thousands of dollars over the life of the debt.
The snowball approach targets the smallest balance instead. You eliminate that loan entirely, then redirect its payment upward. Borrowers on personal-finance forums report that crossing a loan off the list creates a momentum boost that prevents them from giving up midway through a multi-year payoff. If your rates are clustered within a point or two of each other, the interest difference between the methods shrinks and snowball's motivational edge can outweigh the modest math advantage of avalanche.
Rate Spread, Loan Count and the Hybrid Path
A wide rate spread strongly favours avalanche because you stop the most expensive interest first. A narrow spread makes the order less consequential, so borrower behaviour becomes the deciding factor. Some borrowers use a hybrid: knock out one small balance for a quick win, then switch to strict avalanche ordering for the remaining loans. This captures the psychological spark without sacrificing meaningful interest savings over the full payoff period.
Before deciding on an order, check whether any of your loans are federal. If you are considering refinancing federal loans into a single private loan to simplify the process, remember that converting federal debt means permanently losing access to income-driven repayment, forgiveness programmes, and federal forbearance protections. The payoff-priority tool can also help you factor in loan type alongside rate and balance when building your personal order.
The calculator does not assume a payoff method. It models both so you can decide based on your own mix of rates, balances and motivation style.
Next in this cluster
Related student loan calculators
- Which Student Loan Should I Pay Off First?
- Student Loan Avalanche Calculator
- Multiple Student Loans Payoff Order Calculator
Sources
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Standard amortisation formula; avalanche and snowball methods as commonly described in consumer-finance literature.
- 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.