Student loan calculator

How this calculator works

This calculator estimates the monthly payment, payoff timeline, total interest, and savings from extra payments for a fixed-rate student loan with an optional grace period before repayment begins.

It uses the loan balance, annual interest rate, repayment term in years, grace-period length, and whether interest accrues during grace to build a month-by-month schedule. During grace, payments are zero but interest may still accumulate depending on your loan type. When repayment starts, the calculator amortizes the balance—including any capitalized grace-period interest—over the remaining term using standard fixed monthly payments.

You can also enter an extra monthly payment to see how much interest you might save and how many months you might shave off the payoff. The baseline schedule without extra payments is compared against the accelerated schedule so the interest savings are visible.

This model reflects standard fixed repayment. It does not simulate income-driven plans, deferment, forbearance, consolidation, forgiveness, or variable rates. Use it to understand the math behind a straightforward repayment path and to stress-test how grace-period accrual and extra payments change the outcome.

The month-by-month schedule separates grace-phase rows from repayment-phase rows so you can see when interest accumulates without payments and when principal reduction begins. Total interest combines grace accrual plus repayment interest. Interest saved from extra payments compares your accelerated scenario against the baseline with no extra amount.

What affects the result

Several inputs drive the payment and total cost. Small changes in any of them can shift the monthly amount or lifetime interest meaningfully.

• Loan balance is the principal owed when modeling begins. If unpaid interest from grace is capitalized, include that in the starting balance or enable accrue-during-grace so the calculator adds it automatically.
• Interest rate is the fixed annual percentage. Federal and private rates differ; enter the rate from your current servicer disclosure, not an old promissory note if you have refinanced.
• Repayment term is the number of years of payments after grace ends. A 10-year standard plan means 120 monthly payments once repayment starts—not 10 years from graduation including grace.
• Grace period delays the first payment. Six months is common for many federal loans after leaving school, but private terms vary.
• Accrue during grace determines whether interest builds on the balance while payments are paused. Subsidized federal loans often do not accrue during grace; unsubsidized federal and most private loans usually do.
• Extra monthly payment reduces principal faster once repayment begins, lowering total interest and potentially shortening the term below the entered repayment length.

A longer term lowers the monthly payment but increases total interest. A shorter term does the opposite. Grace-period accrual that is not paid before repayment begins raises the balance entering amortization, which increases both payment and total interest.

Payment size follows standard amortization on the post-grace balance. At 0% interest, the payment would simply divide the balance by the number of months. At positive rates, early payments carry more interest and less principal; later payments flip that mix. Extra payments accelerate principal reduction in every month they are applied.

Federal loan types differ in ways this single-loan model cannot fully represent. Direct subsidized loans, Direct unsubsidized loans, PLUS loans, and private refinances each carry distinct grace rules, rate sources, and servicer workflows. Enter the terms that match the loan you are modeling today, not terms from an original disclosure if the loan has changed.

Real-world examples

Unsubsidized federal loan after graduation. You owe $28,000 at 5.5% with a 6-month grace period where interest accrues, followed by a 10-year standard plan. Enable accrue during grace to see how roughly $770 in unpaid interest may capitalize into the balance before the first payment. Compare the monthly payment and total interest with and without a $50 extra payment each month once repayment starts.

Subsidized federal loan with no grace accrual. The same $28,000 at 5.5% with grace accrual turned off keeps the balance flat during grace. Payments begin on the original principal. The difference between subsidized and unsubsidized treatment can be thousands of dollars over the life of the loan.

Private refinance scenario. After comparing servicer quotes, you model a $35,000 balance at 4.9% over 7 years with no grace period because refinancing starts repayment immediately. Use the loan payment calculator to cross-check the monthly payment on a generic installment loan with the same balance, rate, and term.

Multiple debts alongside a student loan. If you also carry credit card balances, run the student loan estimate here, then compare payoff order across all debts with the debt payoff calculator or build a momentum-focused plan with the debt snowball calculator. High-rate revolving debt sometimes deserves extra cash flow even when student loans feel larger.

Extra payments with uncertain cash flow. Model $0, $75, and $150 extra payments. If only the smallest extra amount is sustainable long term, that plan beats an aggressive extra payment you abandon after a few months.

Graduate with multiple loans. If you have four separate federal loans with identical rates and terms, some borrowers treat them as one combined balance for rough planning. Servicers still apply payments per loan, so official quotes may differ slightly from a single combined model. For precise multi-loan sequencing, use the debt payoff calculator with each balance listed separately.

Parent PLUS planning. A $45,000 PLUS loan at 7.5% over 10 years with no grace accrual toggle needed if repayment begins immediately. Compare the monthly payment here against your household budget before choosing an extended or graduated plan with your servicer—those alternatives are not modeled in this tool.

Common mistakes

Treating the repayment term as total time since graduation. A 10-year plan usually means 10 years of payments after grace, not 10 years from your last day of class. Misreading this inflates or deflates the expected payment.

Ignoring grace-period interest on unsubsidized loans. Unpaid interest that capitalizes increases the principal before payment one. Borrowers who assume the original disbursement amount is still the balance can underestimate their payment.

Assuming this calculator models income-driven repayment. IDR plans cap payments as a percentage of income and may forgive remaining balances after qualifying periods. This tool shows fixed amortization only.

Entering the wrong rate after consolidation or refinance. Always use the current weighted or refinanced rate, not historical per-loan rates if those no longer apply.

Expecting extra payments to apply automatically without servicer instructions. Some borrowers must specify that additional amounts go to principal or to a particular loan. Confirm allocation rules with your servicer.

Comparing federal benefits to private refinance math alone. Lower private rates can save interest but may forfeit federal protections such as IDR, certain deferment options, and potential forgiveness programs. The calculator shows cost math, not benefit tradeoffs.

Using estimated balance instead of servicer balance. Interest capitalizes at slightly different times depending on servicer processing. Log in and use the repayment-start balance shown there for the most accurate comparison.

Modeling deferment as grace. Deferment and forbearance have distinct rules for interest subsidy and capitalization. This calculator's grace toggle is not a full deferment simulator.

When to use this calculator

Use this calculator when you want a clear picture of standard fixed repayment on a single student loan—or a consolidated balance you are treating as one fixed loan. It is especially useful during grace when you are building a post-graduation budget, when evaluating whether to pay interest during grace, and when deciding how much extra payment you can sustain.

Use it alongside—not instead of—your servicer's official repayment dashboard before making enrollment decisions. For multi-debt strategies, pair results with the debt payoff calculator. For generic installment math without grace logic, the personal loan calculator and loan payment calculator provide complementary views.

Do not rely on this tool alone if you are evaluating income-driven repayment, Public Service Loan Forgiveness, deferment, or forbearance. Those programs change payment amounts and timelines in ways this fixed model cannot capture.

Review results whenever your rate, balance, or employment status changes materially. Refinancing, consolidation, or a lump-sum payoff from a bonus each warrant a fresh calculation. Export or note your inputs if you compare scenarios over several weeks while deciding on a repayment strategy.

Related calculators

• Debt payoff calculator — Compare snowball and avalanche strategies across multiple debts, including student loans alongside credit cards.
• Debt snowball calculator — Build a month-by-month snowball plan if you prefer targeting the smallest balance first for momentum.
• Loan payment calculator — Estimate fixed payments on any installment loan without grace-period logic.
• Personal loan calculator — Model consolidation or refinance scenarios as a standard personal loan.
• Credit card payoff calculator — Estimate payoff time on revolving balances that may compete with student loan extra payments for your cash flow.