Student Loan Payoff Calculator

What plan should you pick?

Federal student loans give you four practical choices: Standard 10-year, Graduated, Extended, and Income-Driven (a family of plans). The calculator above models the three that matter most — Standard, Extended 25-year, and a representative Income-Based plan with 20-year forgiveness.

The right choice usually depends on three things:

• Your income relative to your loan balance. If your loan total is roughly your annual income or less, Standard 10-year is almost always cheapest. If your balance is 1.5–2× your income, IDR starts to make sense as a hedge.
• Whether you'll qualify for PSLF. If you work for a 501(c)(3) nonprofit or government and plan to keep doing so for 10 years, IDR + PSLF is usually the dominant choice — your remaining balance is forgiven tax-free after 120 qualifying payments.
• Your tolerance for keeping a balance for 20+ years. Even if IDR math wins, some people prefer the psychological closure of paying off in 10. Both are defensible.

How the math works

Standard 10-year and Extended 25-year use the same amortization formula as a mortgage:

P = L · r · (1+r)^n / ((1+r)^n − 1)

Where L is loan balance, r is monthly interest rate (APR ÷ 12), n is total months (10 × 12 or 25 × 12). Payment is fixed; interest paid is front-loaded.

Income-Based works differently. Each month:

discretionary = AGI − 1.5 × poverty_line(family_size)
monthly_payment = max(0, 0.10 × discretionary / 12)

The federal poverty line in the contiguous US is roughly $15,060 for a single person, plus $5,380 per additional family member (2024 figures, updated annually). 150% of that becomes your "shielded" income; the rest is what IDR taxes at 10%.

Crucially: if your IDR payment is less than the monthly interest, your balance grows. That's by design — IDR is meant as an affordability cushion, not a payoff strategy. At year 20, whatever's left is forgiven (subject to current tax rules).

IDR isn't a payoff plan. It's an income cushion that ends in forgiveness.

Income-Driven Repayment in detail

The federal IDR family includes IBR, PAYE, REPAYE/SAVE, and ICR. They differ in:

• Income percentage: 5–15% of discretionary income, depending on plan and loan vintage.
• Discretionary definition: 100–225% of poverty line is "shielded."
• Forgiveness timeline: 20 years for undergraduate-only loans, 25 years for any graduate loans (under most plans).
• Subsidized interest: SAVE notably waived unpaid monthly interest; legal status of that has been contested.

Our calculator models a representative 10%/20-year setup for simplicity. To estimate your exact monthly payment under each specific plan — IBR, PAYE, SAVE, and ICR — use the income-driven repayment calculator, which breaks the four plans out side by side. Your actual plan might give a slightly lower payment and slightly different forgiveness math. For an authoritative quote, use the federal Loan Simulator on studentaid.gov.

Should you refinance into private?

Tempting if private rates are 1–2% below your federal rate, but usually a bad trade. Refinancing federal loans to private kills:

• Income-Driven Repayment access
• PSLF eligibility
• Federal forbearance and deferment options
• Death and disability discharge
• Future federal loan-relief programs (which keep happening)

For most borrowers, those options are worth more than the interest savings. Refinance only if all of these apply: high income that's stable, no nonprofit/government work in your future, and a financial cushion that makes the federal safety net irrelevant.

How to pay less

1. If you're on Standard, pay extra principal. Every dollar extra reduces total interest and shortens the loan. Run the calculator with $100/mo extra and see the savings.
2. If you're on IDR, do not pay extra. Extra payments lower the balance that would have been forgiven — they're effectively a transfer from your bank to the federal government. Save them in a brokerage account instead.
3. Recertify income annually for IDR. If your income drops, your payment drops. Don't let an old AGI keep you locked into a higher payment.
4. Use payroll deduction or autopay. Federal servicers often discount the rate by 0.25% for autopay. Small but free.
5. Aggressively pursue PSLF if eligible. Track your qualifying payments — and certify employment with the federal form annually. Servicers have been known to miscount.
6. For private loans, refinance every 1–2 years. Rates move; lender competition increases over time.

What this calculator doesn't model

• PSLF specifically. 10-year forgiveness for public service requires tracking 120 qualifying payments across employers — too case-specific for a generic calculator. If you're on the PSLF path, model the calculator with the IDR plan and assume 120 months instead of 240.
• Tax of forgiven balance. Federal exclusion expires 2025; state rules vary. The forgiveness number shown is gross — your after-tax outcome may differ.
• Interest subsidies. Some IDR plans subsidize unpaid interest (SAVE notably did before legal challenges). The calculator assumes interest fully accrues to balance.
• Income growth. AGI is treated as constant. In reality, IDR payments grow with income, often shifting IDR vs Standard math materially over a 20-year span.
• Deferments and forbearance. Periods of non-payment usually pause the clock without resetting it. The model assumes continuous monthly payments.
• Capitalization events. Federal loans sometimes capitalize unpaid interest (add it to principal). The calculator's monthly accrual approximates this without modeling the discrete capitalization triggers.