Simple daily interest
Federal student loans charge simple daily interest: balance × rate ÷ 365.25 each day. On $30,000 at 6.52% (the rate for new federal undergraduate loans first disbursed from July 1, 2026 to June 30, 2027), that's about $5.36 a day, or $163.00 for the first month.
Where payment #1 goes
On a standard 10-year schedule, the monthly payment is about $340.95. In month one, $163.00 of it is interest and $177.95 goes to principal, so almost half the payment is interest. Each month the balance drops a little, so a bit less goes to interest and a bit more to principal. That's amortization, and the chart shows the split shifting year by year.
Longer term, lower payment, more interest
Stretching the same $30,000 to 20 years lowers the payment to about $224.03, but total interest roughly doubles, from about $10,914 to about $23,766. At 15 years it's about $261.66 a month and $17,099 of interest. The compare field shows any two terms side by side.
Interest while in school
Subsidized loans don't charge you interest while you're in school at least half-time. Unsubsidized loans do. $5,500 unsubsidized at 6.52% accrues about $0.98 a day, or about $1,613.70 over 54 months of school plus grace. This page shows that simple accrual; if unpaid interest is capitalized (added to the balance), later interest would be charged on the larger balance.
Repayment plans changed
Repayment plan options changed for federal loans made on or after July 1, 2026. This page shows standard fixed-payment math only. Check your loan terms and plan options at studentaid.gov.
What's left out
Autopay rate discounts, the student loan interest deduction, income-driven plans and any forgiveness programs aren't modeled. Private loans can use different interest methods and variable rates; check your lender's terms. Paying extra toward principal shortens the schedule and cuts total interest, because every later month's interest is figured on a smaller balance. You can see the effect by trying a shorter term with the same balance.
Sources
Last reviewed: Sep 28, 2026