How much interest does a student loan add each day, and when does it get added to the balance?
Summary
Federal Direct Loans charge simple daily interest: the principal times the rate, divided by 365.25, for each day since your last payment. At $30,000 and 6%, that is about $4.93 a day. On Direct Loans, unpaid interest is added to principal in only two situations, at the end of a deferment on an unsubsidized loan and when you lose income-based payments on IBR or leave that plan, while consolidation folds any unpaid interest into the new loan's principal.
Four and a half years of interest on one loan
Take a $10,000 Direct Unsubsidized Loan first disbursed in 2026–27 at 6.52%. Nothing is due while the student is in school at least half-time or during the six-month grace period, but interest runs the whole time.
Federal Student Aid tells borrowers to divide by 365.25 to account for leap years. The principal is still $10,000 when repayment starts, because the end of the grace period is not on FSA's list of capitalization events for Direct Loans. The $2,934 does not disappear, though. No payment goes toward principal until all unpaid interest is paid.
On a Standard, Graduated, or Extended plan, each monthly payment covers all the interest that built up since the last one, so no new unpaid interest piles up. It does pile up on an income-driven plan when the payment is smaller than the interest, during any forbearance, and during in-school, grace, and deferment periods on unsubsidized loans. Subsidized loans spare the borrower the interest while in school.
When interest becomes principal
| Loan | Unpaid interest capitalizes |
|---|---|
| Direct Loans and ED-held FFEL loans | After a deferment on an unsubsidized loan; when you no longer qualify for income-based payments on IBR, or leave IBR |
| FFEL loans not held by ED | The same two, plus after a forbearance on any loan and after the grace period on an unsubsidized loan |
FSA's own example shows the cost. A $10,000 Direct Unsubsidized Loan at 6.8% accrues $1.86 a day. After a six-month deferment with no interest paid, $340 capitalizes, the principal becomes $10,340, and daily interest rises to $1.93. Depending on the plan, the monthly payment can go up too.
Consolidation turns unpaid interest into principal
When you combine loans into a Direct Consolidation Loan, any outstanding interest on those loans becomes part of the new loan's original principal. The new fixed rate is the weighted average of the old rates, rounded up to the nearest one-eighth of a percent, and a longer repayment period means more interest overall. The consolidation cannot be reversed. For a private refinance, the site's calculator shows total interest at a lender's top advertised rate.
Sources
- Federal Student Aid, studentaid.gov/understand-aid/types/loans/interest-rates
- Federal Student Aid, studentaid.gov/manage-loans/consolidation
Written by Kaz (pen name). Figures are copied from the sources' published pages on the dates shown. We have not used these products. Corrections: contact form.