Use this student loan repayment calculator to estimate fixed monthly payments, payoff time, deferment interest, total interest, and extra-payment savings.
Student Loan Repayment Formula
For a fixed-rate loan with equal monthly payments, the payment formula is:
M = P * [r(1 + r)^n] / [(1 + r)^n - 1]
If unpaid interest accrues before repayment and is capitalized once, the estimated starting balance is:
P_start = P * (1 + R * t)
Variables:
- M is the fixed monthly payment
- P is the principal balance
- r is the monthly interest rate
- n is the number of repayment months
- R is the annual simple interest rate
- t is the no-payment period in years
Select payment mode to calculate a scheduled payment from a term, with an optional extra amount. Select payoff-time mode to test a monthly payment. The calculator separately reports interest accrued before repayment and interest charged after repayment starts.
Student Loan Payment Reference
The following estimates use a $30,000 balance at 6% with no deferment. Longer terms lower the payment but increase total interest.
| Repayment term | Monthly payment | Interest | Total paid |
|---|---|---|---|
| 5 years | $579.98 | $4,799.04 | $34,799.04 |
| 10 years | $333.06 | $9,967.38 | $39,967.38 |
| 15 years | $253.16 | $15,568.27 | $45,568.27 |
| 20 years | $214.93 | $21,583.04 | $51,583.04 |
Example Problems
Example 1: Calculate a standard fixed payment.
A $35,000 balance enters repayment at 6.5% for 10 years. Enter 120 months through the 10-year term. The calculator applies the amortization formula and reports the payment, repayment interest, and total payoff time.
Example 2: Include six months of accruing interest.
Assume the same $35,000 balance has six months before repayment and the interest is capitalized. Simple accrued interest is approximately $35,000 × 0.065 × 0.5 = $1,137.50, so repayment begins near $36,137.50. The new payment is calculated from that higher balance.
Frequently Asked Questions
Does interest always capitalize during deferment?
No. Treatment depends on the loan type and current rules. Some interest may be subsidized, some may accrue without immediate capitalization, and some may be paid as it accrues. Choose the option that matches the loan documents.
Can this calculate an income-driven payment?
No. Income-driven plans depend on income, household information, eligibility, subsidies, and program rules. This calculator is for fixed-rate payment and payoff planning.
How do extra payments affect student loans?
When applied to principal, extra payments reduce the balance sooner, which lowers future interest and shortens the payoff period. Confirm how the servicer applies amounts above the required payment.
