How the student loan calculator works
This is standard amortization, the same math loan servicers use for fixed-rate loans. The monthly payment is:
Payment = P × r ÷ (1 − (1 + r)−n)
P is the balance, r is the annual rate divided by 12, and n is the number of monthly payments. Each month, interest is charged on the balance you still owe, and the rest of your payment pays down principal. Early on, more of each payment goes to interest. Extra money goes straight to principal, which cuts the interest charged in every month after it.
The calculator assumes a fixed rate and that repayment has started. It doesn't include loan fees or interest that builds up while you're in school. If you have unsubsidized loans, enter the balance you'll owe when repayment begins, not the amount you borrowed.
Federal student loan rates for 2026-27
| Loan | Borrower | Fixed rate |
|---|---|---|
| Direct Subsidized and Unsubsidized | Undergraduate students | 6.52% |
| Direct Unsubsidized | Graduate and professional students | 8.07% |
| Direct PLUS | Parents and graduate or professional students | 9.07% |
For loans first disbursed July 1, 2026 through June 30, 2027. Source: U.S. Department of Education, Electronic Announcement GENERAL-26-33 (June 4, 2026). Check studentaid.gov for rates on older loans.
Worked example
You owe $30,000 in undergraduate federal loans at 6.52% and repay over 10 years.
The monthly payment is $340.95. Over 120 payments you pay about $10,914 in interest.
Add $50 a month and the loan is gone in 100 payments instead of 120. That's 20 months sooner and about $1,992 less interest.
Common questions
What are the federal student loan interest rates for 2026-27?
For loans first disbursed from July 1, 2026 through June 30, 2027: 6.52% for undergraduate Direct Subsidized and Unsubsidized Loans, 8.07% for graduate and professional Direct Unsubsidized Loans, and 9.07% for Direct PLUS Loans. The rates are fixed for the life of each loan.
How are federal student loan rates set?
Each year the rate equals the high yield of the 10-year Treasury note auctioned in May, plus a fixed add-on set by law: 2.05 points for undergraduate loans, 3.60 for graduate unsubsidized loans and 4.60 for PLUS loans. The May 12, 2026 auction yield was 4.468%, which gives the 2026-27 rates. Rates are capped at 8.25%, 9.50% and 10.50%.
Do extra payments go toward principal?
They should, but tell your servicer how to apply them. Ask that extra money go to principal and that it not push back your next due date. Without instructions, some servicers treat an overpayment as an early payment of next month's bill. You can also ask them to put extra toward your highest-rate loan.
Does interest build up while I'm in school?
On unsubsidized and PLUS loans, yes. Interest starts when the money is paid out. On Direct Subsidized Loans, the government covers interest while you're enrolled at least half-time. Enter the balance you'll owe when repayment starts to get an accurate payment.
Does this calculator work for private student loans?
Yes, for fixed-rate private loans. For a variable-rate loan the result is only a snapshot at today's rate, because the payment changes whenever the rate does.