Student Loan Repayment Calculator

Student loan payment calculations use standard loan amortization to determine the fixed monthly payment required to pay off the full balance (including all accrued interest) within the chosen repayment term.

Standard monthly payment formula: M = P × [r(1+r)^n] ÷ [(1+r)^n − 1]

Where:

• M = monthly payment
• P = total loan principal (sum of all disbursements)
• r = monthly interest rate = annual rate ÷ 12
• n = total repayment months (years × 12)

Total cost of loan: Total Paid = M × n

Total interest paid: Interest = Total Paid − P

What each variable means:

• Principal (P): the total borrowed amount. Include all loans if you have multiple.
• Annual Interest Rate: federal undergraduate subsidized loans: ~6.5% (2024). Graduate PLUS loans: ~8%. Private loans: 4–15%.
• Repayment Term: standard is 10 years (120 months). Extended plans stretch to 20–25 years (lower payments but far more interest paid).
• Grace Period: federal loans have a 6-month grace period after graduation. Unsubsidized loans accrue interest during this period, capitalizing at repayment start.

Federal repayment plan comparison ($35,000 at 6.5%):

• Standard 10-year: $397.42/month | Total interest: $12,690
• Extended 20-year: $260.95/month | Total interest: $27,628
• Extended 25-year: $236.32/month | Total interest: $35,897

Read the last row twice. Stretching a $35,000 loan from ten years to twenty-five saves $161 a month and costs an extra $23,000, which is more than half the loan again.

Income-driven plans (IBR, PAYE, SAVE) base payments on income rather than loan balance, useful when income is low relative to debt.

Worked example: Loan balance: $45,000. Interest rate: 6.5%. Term: 10 years.

r = 6.5% ÷ 12 = 0.005417

M = 45,000 × [0.005417 × (1.005417)^120] ÷ [(1.005417)^120 − 1] = 45,000 × [0.005417 × 1.9122] ÷ [0.9122] = 45,000 × 0.011355 = $510.97/month

Total paid = $510.97 × 120 = $61,316 Total interest = $61,316 − $45,000 = $16,316

Refinancing to 4.5% with the same term drops the payment to $466.37 and the total interest to $10,965, a saving of about $5,350 over 10 years. Always compare refinancing offers if your credit score has improved since graduation.

Small extra payments compound fast. One extra monthly payment a year, the classic 13th payment, takes almost exactly a full year off a standard 10-year loan and saves roughly 10% of the total interest. That holds across a wide range of balances and rates, because the 13th payment is the same 8.3% of the total either way. The reason it works at all: every dollar paid against principal early cancels the interest on that dollar for every month that follows. Smaller, consistent extra payments usually beat one large lump sum applied later.

Subsidized vs unsubsidized, the distinction that matters most while you are still in school.

• Subsidized federal loans (Direct Subsidized, for undergraduates with demonstrated financial need): the government pays the interest while you’re in school at least half-time, for 6 months after, and during deferment. No interest accrues during these periods.
• Unsubsidized federal loans (Direct Unsubsidized, available to most students): interest accrues from the day the loan is disbursed, including during school. If you don’t pay the interest as it accrues, it capitalizes (adds to principal) at the end of the grace period. A $25,000 unsubsidized loan at 6.5% can capitalize an extra $3,200+ in interest before you make your first payment.
• Private loans: almost always unsubsidized, often capitalize interest aggressively, and may require in-school payments.

The single best move for unsubsidized borrowers still in school: pay the interest each month from a part-time job or summer earnings. Even $50 a month prevents capitalization and saves thousands long-term.

This page takes a term and works out the payment. If you already have a payment and want to know when the loan ends, the student loan payoff calculator does that, and it will tell you outright when a payment is too small to cover the monthly interest.