Student Loan Calculator

Student loans look like any other amortising debt on a calculator. They aren't. The federal student loan system has its own ecosystem of repayment plans, income-based options, forgiveness programs, and consumer protections that no other type of consumer debt has. Picking the wrong repayment strategy — or refinancing without understanding the trade — can easily cost $20,000–$50,000 over the life of the loan, or leave forgiveness on the table that would have wiped out the balance entirely.

Federal vs. private: a completely different product

Federal loans(Direct Subsidized, Unsubsidized, Grad PLUS, Parent PLUS) come with consumer protections that don't exist anywhere else in lending: income-driven repayment caps, forbearance and deferment options, death-and-disability discharge, and access to forgiveness programs. The rate is set annually by Congress, not by your creditworthiness — currently around 6.5% for undergrads, 8% for graduate students.

Private loansfrom banks and online lenders are credit-priced and structurally identical to personal loans. No income-driven plans. No forgiveness. Limited forbearance. Variable rates often start lower than federal but adjust upward. They're cheaper for borrowers with excellent credit and stable income; they're catastrophic for everyone else when life goes sideways.

The CFPB's student loans toolkitwalks through the current federal program options in detail. If you don't know which type of loan you have, you can look it up at studentaid.gov in 30 seconds.

Income-driven repayment, briefly

For federal loans, IDR plans cap your monthly payment at 5–10% of discretionary income (income minus 150–225% of the federal poverty line, depending on the plan) and extend the repayment term to 20–25 years. The remaining balance is forgiven at the end — though under current tax law that forgiven amount may be taxable.

The plans in active use after the 2024–2025 changes: SAVE (currently in legal limbo), PAYE, IBR, and the new Income-Contingent Repayment (ICR) structure. The standard 10-year plan minimises total interest. The IDR plans minimise monthly payment and add forgiveness at the back end. For borrowers with low income relative to their debt — especially those pursuing public-service careers — IDR is usually the better trade. For borrowers earning well above their debt, the standard plan pays off faster and cheaper.

PSLF: the program everyone gets wrong

Public Service Loan Forgiveness wipes out the remaining balance after 120 qualifying monthly payments (10 years) while working full-time for a qualifying employer — government at any level, 501(c)(3) non-profits, AmeriCorps, Peace Corps. The catch is that every step has to be right: Direct Loans (consolidate if needed), an IDR plan, a qualifying employer at the time of each payment.

The program had a ~98% rejection rate in its early years because the rules were poorly communicated and servicers gave wrong information. The 2022 PSLF Waiver fixed much of that backlog and current approval rates are much higher. If you work in qualifying employment and have federal loans, file an Employment Certification Form annually at studentaid.gov to confirm progress. The cost of doing this is a 20-minute form; the cost of not doing it can be $50,000+ in foregone forgiveness.

Refinancing federal loans is usually a mistake

Private student loan refinance offers — "cut your rate by 2%!" — are widely marketed and look great in spreadsheets. They permanently convert federal loans to private. You lose: income-driven repayment access, PSLF eligibility, the option of federal forbearance during unemployment, death-and-disability discharge, the standard 6-month grace period on job loss. None of those come back.

The math case for federal-to-private refinance only makes sense when (1) your income is high and stable enough that you'll never need IDR, (2) you don't work in qualifying public service, (3) your savings cushion can absorb 12+ months of unemployment, and (4) the rate savings are large enough (typically 2+ percentage points) to actually matter. For private loans, the calculation is simpler: refinance is just a rate shop, with no federal protections to lose.

Pay off vs. invest: the actual math

The right answer depends on your loan rate, not on advice posted on Reddit. Two reference points:

• Loan rate below ~5%: minimum payments plus invest the difference usually wins. Long-run equity returns historically exceed 5%, and the loan interest is partially tax-deductible up to $2,500/year (income-dependent phase-out).
• Loan rate above ~7%: paying down the loan is a guaranteed return at that rate. Beating that with investments is possible but not guaranteed; the "safe" choice is the loan.
• Between 5–7%: pick whichever lets you sleep. The math is roughly a wash.

Universal exception: always contribute enough to your employer 401(k) to capture the full match before any extra loan payments. A 50% or 100% employer match is an immediate guaranteed return that beats any loan rate.

Tactical add-ons most borrowers miss

• •Autopay discount. Federal servicers and most private lenders offer 0.25% off the rate for autopay. On $40,000 over 10 years, that's about $580 saved.
• •Direct-to-principal note. When making extra payments, include a written instruction (online or by letter) that the extra goes to principal, not next month's payment. Servicers default to the wrong thing.
• •Employer student loan benefit. Under the SECURE 2.0 Act, employers can now match student loan payments with 401(k) contributions, treating them as if they were retirement contributions. Worth asking HR about.
• •State-level forgiveness programs. Many states have profession-specific forgiveness (rural physicians, public defenders, special-ed teachers). The American Bar Association and AMA maintain lists worth a five-minute search.