Estimate fixed student-loan payments, grace-period interest, payoff timing, and potential savings from additional principal payments.
This calculator models a fixed-rate installment repayment schedule from principal, interest rate, and term. Optional grace-period interest and extra payments show how the balance can change before and during repayment.
It is an educational projection. It does not model income-driven repayment, forgiveness, subsidies, deferment or forbearance rules, tax effects, or jurisdiction-specific programs.
P is repayment principal, r is monthly interest rate, and n is scheduled payments. At 0%, payment is P ÷ n.
P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1)This initial model uses simple monthly accrual during each selected grace month.
Original principal × annual rate ÷ 12Applies only when capitalization is selected.
Original principal + accrued grace-period interestWith repayment beginning January 1, 2026, no grace period, and no extras, the required payment is $325.58 for 120 payments, with $9,069.46 in estimated interest and payoff on January 1, 2036. Adding $100 per month keeps the required payment unchanged and produces an 86-payment estimate ending March 1, 2033, with $6,316.14 in interest.
A shorter term generally raises the required payment while reducing the time interest accrues.
Capitalized grace interest becomes principal and can generate additional interest during repayment.
Check how the loan servicer applies amounts above the required payment and whether instructions are needed.
A grace period delays modeled repayment. When accrual is enabled, simple monthly interest accumulates on original principal for each grace month.
If capitalized, that interest joins principal before the payment is calculated. If not capitalized, it remains separate; monthly payments cover current interest, then unpaid grace interest, then principal. It is never silently discarded.
Recurring and eligible one-time extras are applied after the required payment. They do not increase the scheduled required payment, but they can reduce principal sooner, shorten payoff, and lower later interest.
The model assumes a fixed rate and monthly interest. Real student loans can use daily interest, different allocation and capitalization rules, fees, subsidies, or repayment programs not represented here.
It uses the standard fixed-rate installment formula on the modeled repayment principal over the selected term.
Only when you enable it. This version uses simple monthly interest on original principal during each grace month.
Capitalized interest is added to principal before repayment, so it can generate interest during the repayment period.
It stays separate and payments cover current interest, then unpaid grace interest, then principal.
No. They are modeled after the required payment and can shorten payoff and reduce interest.
On the first scheduled payment date on or after the selected date.
No. Those program rules are outside this calculator’s fixed-payment scope.
Servicers may use daily interest, contractual allocation and capitalization rules, fees, rounding, and program-specific requirements.