How the student loan calculator works
Enter your loan balance, interest rate, repayment term in years and any grace period in months. Interest that accrues during the grace period is added to the balance, then the calculator works out a standard fixed monthly payment over your repayment term.
The formula
Interest during the grace period = balance × monthly rate × grace months, added to the balance; the payment is then M = P × r(1+r)^n / ((1+r)^n − 1) over the repayment term.
This models a standard fixed repayment plan. Income-driven plans, subsidized loans (where the government pays grace-period interest) and forgiveness programs work differently.
Frequently asked questions
Does interest build up during the grace period?
On most unsubsidized loans, yes. The calculator adds that interest to your balance before repayment starts.
When will my loan be paid off?
The payoff date shown is today plus the grace period plus the repayment term.
Does this work for income-driven repayment?
No — it models a standard fixed plan. Income-driven payments depend on your income and family size.
How can I pay less interest?
Pay the grace-period interest as it accrues, or add extra principal once repayment starts.
Results are estimates for planning, not financial advice. Last reviewed 2026-09-28.