Plan a student loan three ways. The General tab finds the monthly payment (or the missing balance, term, or rate) from any three values. Repayment shows how extra payments or paying the balance in full cut interest versus the current schedule. In school projects the balance through remaining college years and a grace period, then the payment after repayment begins.
Formula
Student loans use the same monthly amortization as other installment loans. Monthly rate r is the annual rate ÷ 12.
Known remaining term. The level payment on principal P over n months is:
payment = P × r / (1 − (1 + r)^(−n))
If the monthly payment is known instead, the calculator simulates month by month until the balance clears (the last payment may be partial).
Extra payments. The current monthly payment is kept; extra monthly, yearly (months 12, 24, …), and one-time (month 1) amounts are added on top. Paying the loan back altogether is a lump-sum payoff of the remaining balance today.
While in school. Each remaining school month, unpaid interest is added and new borrowing of (estimated amount per year) ÷ 12 is disbursed:
balance = balance × (1 + r) + annualAmount / 12
The grace period compounds with no new disbursements. Repayment then amortizes that balance over the loan term. If you pay the interest as it accrues, it never capitalizes and repayment is based on the amount borrowed.
Federal Direct Subsidized Loans typically do not accrue interest during school or the grace period. Unsubsidized and most private loans do. This calculator does not include origination fees or income-driven plans.
Federal repayment plans at a glance
| Plan | Typical length | Payment | Forgiveness? |
|---|---|---|---|
| Standard | 10 years | Fixed | No |
| Graduated | 10 years | Increases every two years | No |
| Extended | up to 25 years | Fixed or graduated | No |
| Income-driven (IBR, PAYE, SAVE/ICR) | 20–25 years | Based on discretionary income | Yes, at the end of the term |
Most borrowers start on the Standard plan — the default if no other plan is chosen.
Examples
$30,000 remaining · 10 years · 6.8%
The standard payment is $345.24 a month. You repay $41,428.92 in total, of which $11,428.92 is interest (about 28% of every dollar paid).
Same loan, $350/month plus $150 extra
At $350 a month the remaining term is 9 years and 10 months. Adding $150 extra each month pays it off in 6 years and 2 months — 3 years and 8 months earlier — and saves $4,421.28 of interest.
$20,000 current · $10,000/year for 2 more years · 6-month grace
You will have borrowed $40,000. If interest is not paid in school, the balance is about $44,264 at graduation and $45,790 after the grace period, with a $526.96 monthly repayment and $23,234.95 of total interest.