Student Loan Calculator

Federal and private student loans amortize like any other fixed-rate installment loan. The monthly payment is calculated so that equal payments over the chosen term retire both the principal and all accrued interest. Interest is charged on the outstanding balance, so the early payments are interest-heavy and the later ones are principal-heavy.

Federal loans accrue interest daily using a simple daily interest formula: balance multiplied by the annual rate, divided by 365. That daily figure matters more than borrowers expect. On a $35,000 balance at 6.5%, roughly $6.23 in interest accrues every single day, or about $190 a month before any payment is applied.

Payments are applied first to any outstanding fees, then to accrued interest, and only then to principal. If you pay less than the accrued interest in a month, the shortfall may capitalize — get added to principal — and you begin paying interest on interest. This is the mechanism that leaves some borrowers with a larger balance years into repayment than the amount they originally borrowed.

The standard federal repayment plan is ten years. Extended and graduated plans stretch the term to lower the payment, which always increases total interest. Income-driven plans set the payment as a share of discretionary income instead of a fixed amortization, which is a different calculation entirely and can leave a forgivable balance at the end.

Federal loans carry fixed rates set by Congress for each academic year, and they come bundled with protections that have real financial value: income-driven repayment, deferment and forbearance, death and disability discharge, and access to forgiveness programs. Those protections are the reason most advisers urge caution before refinancing federal debt away.

Private loans are underwritten on credit and income, may carry fixed or variable rates, and typically offer only limited hardship options. A strong borrower can sometimes refinance private debt to a materially lower rate, and there is little downside to doing so because few protections are being surrendered.

Refinancing federal loans into a private loan is irreversible. You permanently give up income-driven repayment, any path to Public Service Loan Forgiveness, and the generous federal hardship provisions. The rate savings must be large enough, and your income stable enough, to justify losing that insurance.

Subsidized federal loans do not accrue interest while you are enrolled at least half time or during certain deferments. Unsubsidized loans and virtually all private loans accrue from disbursement, which is why a borrower can graduate owing several thousand dollars more than they were handed.

Income-driven plans set the monthly payment at a percentage of discretionary income — broadly, income above a multiple of the federal poverty guideline for your household size — and extend the term to twenty or twenty-five years, with any remaining balance forgiven at the end. Payments recertify annually as income and family size change.

These plans lower the monthly payment but usually increase total interest paid, sometimes dramatically, because the balance is outstanding much longer. The trade-off is worth it when the payment on a standard plan is genuinely unaffordable, or when you are pursuing forgiveness and are deliberately minimizing what you pay along the way.

Public Service Loan Forgiveness cancels the remaining federal Direct Loan balance after 120 qualifying monthly payments while working full time for a government or qualifying nonprofit employer. For borrowers on that path, paying extra is counterproductive — every additional dollar reduces the amount that would eventually be forgiven.

Forgiveness under standard income-driven plans arrives after twenty or twenty-five years and has historically been treated as taxable income at the federal level in some periods. Anyone planning around long-horizon forgiveness should model a potential tax bill in the forgiveness year and confirm current rules, which change with legislation and administrative action.

Because rules shift, verify your specific situation with your loan servicer and the current federal student aid guidance before making a decision you cannot undo, such as refinancing or consolidating.

On a fixed-rate loan you are not pursuing forgiveness on, every extra dollar of principal permanently cancels all future interest that dollar would have carried. That is a guaranteed return equal to your interest rate — no market risk, no sequence risk, no fees.

On a $35,000 balance at 6.5% over ten years, the required payment is about $397 and total interest is roughly $12,700. Add $150 a month and the loan clears in about seven years and total interest drops by roughly $3,700. The savings scale with how early the extra payments start.

Order of operations matters. Capture any employer retirement match first — a 50% or 100% match beats any loan rate in the country. Then clear credit card debt, which routinely runs two to four times a student loan rate. Then keep a basic emergency fund, because student debt is not dischargeable in bankruptcy and a missed payment during a job loss is expensive.

If you carry several loans, target the highest rate first while paying the minimum on the rest. That is the mathematically optimal order. If motivation is the binding constraint rather than math, clearing the smallest balance first is a defensible alternative — the plan you actually follow beats the plan that is theoretically optimal.

Always specify that extra payments apply to principal on the highest-rate loan. Left unmarked, servicers commonly spread extra funds proportionally across all loans or advance your due date instead, which wastes most of the benefit.

A common guideline is that total student loan payments should stay under roughly 10% of gross income, and that total borrowing should not exceed the first-year salary the degree realistically produces. Beyond that, the payment starts crowding out retirement saving, housing, and emergency reserves at precisely the age when compounding matters most.

The calculator shows your payment as a share of gross income so you can test that guideline directly. If the figure runs into the high teens or beyond, an income-driven plan or a longer term is likely the pragmatic choice, even though it costs more interest.

Student loan payments also count in the debt-to-income ratio a mortgage lender uses. Lenders generally treat a documented income-driven payment as the qualifying figure, so lowering your student loan payment can materially increase how much house you qualify for — a trade-off worth modeling explicitly if a home purchase is on the horizon.

Autopay usually earns a small interest rate reduction on federal loans and many private loans. It is a free rate cut and it eliminates the risk of a missed payment damaging your credit, so enroll unless your cash flow is genuinely unpredictable.

Enter your total current balance across the loans you want to model. If your loans carry very different rates, run them separately for a more accurate picture, or use a balance-weighted average rate as an approximation.

Enter the annual interest rate as a percentage and the repayment term in years. Ten years is the federal standard; extended and refinanced terms commonly run fifteen, twenty, or twenty-five years.

Add any extra monthly principal payment you plan to make. The results show your required payment, the payoff time including the extra amount, total interest, and how much interest and time the extra payment saves compared with paying the minimum.

Enter your gross annual income to see the payment as a share of income. Use pre-tax income for the standard comparison against the 10% guideline.

Results are estimates for a fixed-rate, standard-amortization loan. They do not model income-driven formulas, interest subsidies, capitalization events, or forgiveness. Confirm the specifics of your own loans with your servicer.