Multi-loan student loan payoff calculator

How this calculator works

This calculator models up to ten student loans side by side. Each loan has its own balance, fixed interest rate, repayment term, grace period, and optional deferment window. During grace or deferment, payments are zero and interest may accrue depending on your settings — matching subsidized vs. unsubsidized federal behavior. Once repayment starts, each loan uses standard fixed-rate amortization. You can add a global extra monthly payment and choose whether it follows avalanche (highest rate first), snowball (lowest balance first), or proportional allocation. The tool totals minimum payments, interest, payoff timing, and plots each loan's balance over time plus a combined line when multiple loans are present.

The model assumes fixed minimum payments for the full term — it does not recalculate when you pay off individual loans early beyond routing extra dollars correctly. For income-driven federal payments that change annually, use the plan comparison calculator instead. The read your statement reference helps verify balances before you enter them.

What affects the result

Interest rate ordering drives avalanche vs. snowball differences. Higher-rate loans generate more interest per dollar of balance, so sending extra to them saves more over time. Grace period settings change the balance that enters repayment — unsubsidized loans that accrue during a six-month grace period start repayment above the original disbursement amount. Deferment months pause payments; if interest accrues and is not paid, the balance grows before amortization resumes. Extra payment amount and strategy directly shift the debt-free date. Term length per loan changes the required minimum payment independently for each entry.

Real-world examples

Example 1 — Subsidized + unsubsidized federal mix: A borrower has $15,000 Direct Subsidized at 6.53% (no grace interest) and $12,000 Direct Unsubsidized at 6.53% with six-month grace that accrues. The unsubsidized loan starts repayment with a higher balance, so identical rates do not mean identical payoff timing.

Example 2 — Avalanche with $100 extra: Loan A is $8,000 at 7.5%; Loan B is $20,000 at 5.5%. Avalanche sends the full $100 to Loan A until it is gone, then to Loan B — usually the lowest total interest path.

Example 3 — Snowball for momentum: Loan A is $4,000 at 6%; Loan B is $18,000 at 6.8%. Snowball clears the $4,000 loan first even though B has the higher rate, trading a small amount of interest for a faster first payoff.

Example 4 — Deferment after repayment starts: A borrower pauses payments for months 18–24 with interest accruing. The chart shows balance rising during that window and a later debt-free date compared with continuous repayment.

Example 5 — Parent PLUS alongside Direct: A family holds $22,000 Parent PLUS at 8.05% and $18,000 Direct Unsubsidized at 6.53%. Avalanche sends all extra to the PLUS first, saving more interest than snowball despite the smaller undergrad balance being easier to clear first.

Example 6 — Auto-pay discount: Both loans qualify for 0.25% auto-pay reductions. Entering 6.28% instead of 6.53% on each loan slightly shortens payoff — a small but real savings worth modeling if you plan to enroll.

Common mistakes

Entering balance at graduation instead of after grace. If interest accrued during grace, enter the balance that will be due when payments start — or model grace explicitly.

Same rate assumption for all loans.Grad PLUS, private refi, and older loans may carry different rates. Enter each loan's actual rate.

Forgetting minimum payments stack. Total monthly minimum is the sum across loans, not a single payment for the portfolio.

Choosing snowball without comparing avalanche. Run both strategies with your extra amount to see the interest cost of snowball.

Modeling IDR minimums here. Income-driven payments change annually. Use the plan comparison calculator for IDR, not this fixed-amortization tool.

Ignoring auto-pay rate discounts. Many servicers cut 0.25% with auto-pay. Lower the rate slightly if that applies.

When to use this calculator

Use this when you hold multiple federal or private loans with different rates and want a combined payoff date, total interest estimate, or comparison of avalanche vs. snowball. It is ideal for new graduates mapping grace periods, borrowers allocating a fixed extra payment, or anyone planning whether to attack one loan aggressively. For a single simplified estimate, the standalone student loan calculator still works for one loan at a time. If a pause is under consideration, model its cost with the deferment cost calculator.

Limitations

Income-driven repayment, PSLF, and federal forgiveness are not modeled. Variable-rate private loans are treated as fixed at the rate you enter. Capitalization events outside your specified deferment window are not captured. Servicer rounding and payment due-date quirks may differ slightly from this simulation. Consolidation into a single new loan is not modeled — enter post-consolidation balances manually if you consolidate. Minimum payments are not recalculated when individual loans pay off early.

Sources

1. Federal Student Aid — Direct Subsidized and Unsubsidized Loans
2. Federal Student Aid — Repayment