Student Loan Interest Calculator
A student loan interest calculator shows the total interest you'll pay over your loan's life — and how much of it extra payments can erase. Interest is the quiet half of every payment; enter your numbers below to see yours.
Yearly amortization (with extra payments)
| Year | Principal paid | Interest paid | Remaining balance |
|---|---|---|---|
| Year 1 | $4,045 | $2,040 | $32,955 |
| Year 2 | $4,286 | $1,799 | $28,669 |
| Year 3 | $4,542 | $1,543 | $24,127 |
| Year 4 | $4,812 | $1,273 | $19,315 |
| Year 5 | $5,099 | $986 | $14,216 |
| Year 6 | $5,402 | $682 | $8,814 |
| Year 7 | $5,724 | $361 | $3,090 |
| Year 8 | $3,090 | $54 | $0 |
How student loan interest actually works
Student loans use simple daily interest. Your annual rate is divided by 365, charged on your balance every day, and your monthly payment covers that interest first — whatever is left pays down principal. Early in the loan, interest eats most of your payment; that's why the first years feel like standing still.
Daily interest cost = (balance × rate) ÷ 365. On a $37,000 loan at 5.8%, that's about $5.88 every single day — before any principal.
Why the totals above are so large
On a standard 10-year plan at 5.8%, a $37,000 loan accrues roughly $11,800 in interest — about 32% of everything you borrowed. The green numbers in the calculator show how much of that a modest extra payment removes: interest saved compounds monthly because each dollar of principal you kill early stops charging interest for the rest of the term.
Read the payment timing details
See how student loan interest accrues and payments are allocated for the daily-interest mechanics. For a different payment cadence, read what biweekly student loan payments can and cannot save.
This calculator is for educational purposes only and is not financial advice. Actual interest depends on your servicer's exact day-count conventions; check your statement or studentaid.gov for official figures.