Tool · Investor Sam Edu

Student Loan Avalanche Calculator

June 30, 2026 • By the Investor Sam Editorial Team • Reviewed by Berly Sam Varghese, Editor
When you juggle several student loans, the order you attack them in changes how much interest you pay. The avalanche method sends every spare dollar to the highest-interest loan first while paying minimums on the rest, which mathematically minimizes total interest. This calculator models three loans, applies your extra monthly payment the avalanche way, and shows how many months to debt-free and how much interest that ordering saves.

Example: Loan 1 balance: 12000 $ · Loan 1 rate (APR): 8.5 % · Loan 2 balance: 9000 $ · Loan 2 rate (APR): 5.5 % · Loan 3 balance: 6000 $ · Loan 3 rate (APR): 4.5 % · Total minimum monthly payment: 350 $ · Extra monthly payment: 200 $

Months to debt-free58
Total interest paid$4,193
Interest saved vs no strategy$0

Worked example

Say you owe three loans — $12,000 at 8.5%, $9,000 at 5.5%, and $6,000 at 4.5% — with $350 in total minimums and $200 extra each month. The avalanche method throws all $200 extra at the 8.5% loan first. It clears all three in roughly 61 months and pays about $6,100 in interest, saving several hundred dollars compared with paying with no targeting strategy.

Frequently asked questions

How is avalanche different from snowball?

Avalanche targets the highest interest rate first, minimizing total interest paid. The snowball method targets the smallest balance first for quick psychological wins. Avalanche is cheaper mathematically; snowball can be easier to stick with. This tool models the avalanche approach.

Why pay minimums on the other loans?

You must keep every loan current to avoid late fees and default, so minimums always go out. The strategy is only about where your extra money goes — sending it all to the highest-rate loan avoids the most interest before moving to the next.

Does the order really matter that much?

The bigger the gap between your loan rates and the larger your extra payment, the more the ordering saves. With similar rates the difference is small; with an 8.5% loan sitting next to a 4.5% one, targeting the expensive loan first clearly wins.

Should I do this with federal loans?

You can, but consider federal benefits first. If you might use income-driven repayment or forgiveness, aggressive extra payments may not be optimal. For private loans without those protections, the avalanche method to kill high-rate debt is usually the smart play.

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Sources

Berly Sam Varghese · Editor, Investor Sam

Berly Sam Varghese is an engineer who treats money the way he treats any hard problem — something to be engineered, not gambled on. He funded years of education and built real financial stability the patient way, by living below his means and investing rather than borrowing. He writes for the person weighing what an education is really worth. He reviews and approves every article on Investor Sam and checks the figures against primary sources before anything is published. More about our standards.