Student Loan Repayment Calculator

Calculate your student loan monthly payment, total interest, and payoff timeline. See how extra payments accelerate payoff.

This calculator projects your Student Loan Repayment using the standard fully-amortizing formula (lines 12-16) to compute a Monthly Payment from Loan Balance, Interest Rate, and Loan Term, then simulates the payoff month by month (lines 28-45) so an Extra Monthly Payment can be layered on top. At the default $0 Extra Monthly Payment, Payoff Time is driven entirely by Loan Term — dial Loan Term down 10% and then up 10% from its default, and Payoff Time swings by exactly 20% end to end, while doing the same to Loan Balance or Interest Rate leaves Payoff Time completely unchanged, because a fully-amortizing standard payment is defined to retire the loan in precisely Loan Term times 12 months regardless of how large the balance or rate is. Interest Saved (Extra Payments) tells the same story from the other side: with no extra payment entered, it stays exactly $0 no matter what Loan Balance, Interest Rate, or Loan Term are set to, because the field measures the benefit of the Extra Monthly Payment specifically — set that field above $0 (it defaults to $0 whenever it is left blank or entered as a literal zero) and both Interest Saved and Time Saved start moving. Monthly Payment is dominated by Loan Balance: its ±10% span is about 20% of Monthly Payment, versus only roughly 15% for Loan Term and about 5% for Interest Rate at the default 5.5% rate. Total Interest Paid, by contrast, responds almost identically to Interest Rate (about 22%) and Loan Term (about 21%), with neither one a clear leader over the other, since both feed the same compounding calculation that produces Monthly Payment. This calculator does not model income-driven repayment plans, loan forgiveness, deferment, or capitalized interest — it assumes a single fixed rate applied every month from day one.