Student Loan Calculator

How Student Loan Payments Are Calculated

Standard and Extended repayment plans use the same amortization formula as a mortgage: M = P × [r(1+r)ⁿ] ÷ [(1+r)ⁿ − 1], where P is your loan balance, r is the monthly interest rate (annual rate ÷ 12), and n is the number of monthly payments (years × 12).

Income-Based Repayment (IBR) works differently. Your payment is based on your income, not your loan balance:

• Discretionary income = Adjusted Gross Income − 150% of the federal poverty line ($15,060 for a single person in 2024)
• IBR payment = 10% of discretionary income ÷ 12 (for new borrowers after July 2014)
• If your IBR payment is less than the accruing interest, your balance can grow — this is called negative amortization

This calculator shows results for your selected plan, plus a side-by-side comparison of all three plans.

Federal vs. Private Student Loans

The type of loan you have dramatically affects your repayment options:

Federal student loans (Direct Subsidized, Direct Unsubsidized, PLUS loans) offer:

• Income-driven repayment plans (IBR, PAYE, SAVE, ICR)
• Public Service Loan Forgiveness (PSLF)
• Deferment and forbearance options
• Fixed interest rates set by Congress each year
• No credit check required for most federal loans
• Discharge options in cases of school closure, disability, or death

Private student loans (from banks, credit unions, online lenders) offer:

• Potentially lower interest rates for borrowers with excellent credit
• Fixed or variable rate options
• None of the federal protections above — no IDR, no PSLF, limited hardship options
• Cannot be refinanced into federal loans (only the other direction)

The general rule: exhaust federal loan options first. Federal protections have real financial value that private loans simply cannot match.

Standard vs. Income-Driven Repayment Plans

The choice of repayment plan is one of the most consequential financial decisions a student loan borrower makes:

Standard Repayment (10 years): Fixed equal payments over 120 months. You pay the least total interest of any plan. This is the "default" plan and often the best choice if you can comfortably afford the payment. A $35,000 loan at 6.5% has a $397/month standard payment.

Extended Repayment (25 years): Lower monthly payment but dramatically more total interest. The same $35,000 loan has a $249/month extended payment — saving $148/month — but costs $39,600 more in total interest over the life of the loan. Best for borrowers with high debt relative to income and no plans to pursue forgiveness.

Income-Driven Repayment (IDR): Payment is capped as a percentage of discretionary income. The key advantage is that remaining balances are forgiven after 20–25 years of payments (taxable forgiveness) — or 10 years for PSLF (tax-free). IDR may result in paying less than the interest accruing, causing balance growth, but the forgiveness backstop limits ultimate liability.

SAVE, IBR, PAYE: Comparing Income-Driven Plans

The federal government offers multiple IDR plans, each with different rules:

• SAVE (Saving on a Valuable Education): The newest plan (2023). Payment = 5% of discretionary income above 225% of poverty line for undergraduate loans; 10% for graduate. Most generous discretionary income calculation. No negative amortization — if your payment doesn't cover interest, the government waives the excess interest. Forgiveness at 10–25 years depending on loan size. Currently under legal challenge as of 2024.
• IBR (Income-Based Repayment): 10% of discretionary income (above 150% poverty line) for new borrowers after July 2014; 15% for older loans. Forgiveness at 20 years for new borrowers, 25 years for older. Available for Direct and FFEL loans.
• PAYE (Pay As You Earn): 10% of discretionary income, but capped so you never pay more than Standard plan amount. Forgiveness at 20 years. Must be a "new borrower" as of October 1, 2007 with no Direct loans before October 1, 2011.
• ICR (Income-Contingent Repayment): 20% of discretionary income or what you'd pay on a 12-year fixed plan, whichever is less. Forgiveness at 25 years. The only plan available for Parent PLUS loans (after consolidation).

Public Service Loan Forgiveness (PSLF)

PSLF is one of the most valuable student loan benefits available — and one of the most misunderstood. Key requirements:

• Work full-time for a qualifying employer: federal, state, local, or tribal government; 501(c)(3) nonprofit organizations; certain other nonprofits providing qualifying public services
• Have Direct Loans (or consolidate FFEL loans into Direct Consolidation Loans)
• Enroll in a qualifying repayment plan (any IDR plan, or Standard 10-year)
• Make 120 qualifying payments (10 years) — payments don't need to be consecutive
• Submit annual Employment Certification Forms (now called PSLF Form) to track progress

The forgiveness under PSLF is tax-free, unlike standard IDR forgiveness (which is treated as taxable income). For a borrower with $100,000 in debt earning $55,000/year, PSLF could result in total payments of $50,000–$60,000 with the remaining $50,000–$80,000 forgiven — a massive benefit.

Historically, PSLF had a very low approval rate due to paperwork errors and incorrect loan types. The PSLF Waiver in 2021–2022 and subsequent program improvements have significantly improved outcomes. Use studentaid.gov to track qualifying payments.

Refinancing Student Loans: Pros and Cons

Private refinancing replaces your existing loans (federal or private) with a new private loan at a new interest rate. The math can look attractive — but the trade-offs are significant for federal loans.

Pros of refinancing:

• Lower interest rate (especially for borrowers with strong credit and income)
• Single servicer instead of multiple loans
• Potential to choose a shorter term and pay off faster

Cons of refinancing federal loans privately:

• Permanently lose access to IDR plans
• No longer eligible for PSLF — this alone can be worth tens of thousands of dollars
• Lose deferment, forbearance, and discharge protections
• Cannot return to federal loans once refinanced privately

Rule of thumb: only refinance federal loans privately if you are certain you will not pursue PSLF, your income is high enough that IDR plans offer no benefit, and the rate reduction is meaningful enough to justify the lost protections.

Avalanche vs. Snowball for Student Loan Payoff

If you have multiple student loans, your payoff strategy matters:

Debt avalanche: Pay minimums on all loans, direct extra payments to the highest-interest loan first. Mathematically optimal — saves the most in total interest. Typically recommended for student loans because the interest rate differences between loans can be significant (e.g., 7.5% grad PLUS vs. 4.5% undergrad subsidized).

Debt snowball: Pay minimums on all loans, direct extra payments to the smallest balance first regardless of rate. Psychologically motivating — eliminates loan accounts faster. If the interest rate differences between your loans are small (<1%), the psychological benefit of the snowball may outweigh the marginal interest cost.

For federal loans with IDR plans, there's a third consideration: if you're pursuing PSLF, you actually want to pay as little as possible on high-balance loans (maximize forgiveness), so throwing extra money at principal works against you. In that case, make minimum IDR payments and invest the difference.

The Student Loan Interest Tax Deduction

The IRS allows a deduction of up to $2,500 in student loan interest per year. Key rules:

• Available for both federal and private loans
• You (not your parents) must be legally obligated to repay the loan
• Phase-out range for 2024: $75,000–$90,000 MAGI (single), $155,000–$185,000 (married filing jointly)
• Above these thresholds, the deduction is unavailable
• It's an "above-the-line" deduction — you don't need to itemize to claim it

At the 22% tax bracket, the full $2,500 deduction saves $550 in federal taxes annually. It's automatic on your 1098-E form from your servicer — don't miss it.

What Happens If You Default on Student Loans?

Federal student loan default (270+ days past due) triggers severe consequences:

• The entire loan balance becomes immediately due
• Tax refunds and Social Security payments can be garnished without a court order
• Up to 15% of disposable wages can be garnished
• Credit score damage (major derogatory mark)
• Loss of eligibility for additional federal student aid
• Collection fees of up to 25% added to balance

The key federal protection: IDR plans prevent default for almost anyone with federal loans. Your payment can be as low as $0/month on IDR if your income is below 150% of the poverty line (~$22,590 in 2024). If you're struggling, switch to an IDR plan before defaulting.

If you have defaulted: federal loans can be rehabilitated (9 monthly payments in 10 months removes default status and the derogatory mark), or consolidated through Direct Consolidation to regain good standing. Contact your servicer or studentaid.gov immediately.