Student Loan Calculator

Use this student loan calculator to estimate monthly payments, total interest, and payoff date. It’s designed for borrowers and families comparing options, modeling grace periods and capitalization, and assessing the impact of fees and extra payments.

Enter your loan details

Interest capitalization at repayment start

Results

Monthly payment $0.00
Total interest $0.00
Total paid $0.00
Payoff time 0 months
Estimated payoff date —

Principal after capitalization: $0.00 · Estimated net disbursement (after fee): $0.00

About this student loan calculator

This professional-grade student loan calculator uses standard amortization mathematics and optional capitalization to model how your balance evolves from disbursement through repayment. It helps you compare scenarios, plan extra payments, and understand trade-offs before you borrow—or while you’re repaying.

Data Source and Methodology

Authoritative sources:

  • U.S. Department of Education – Federal Student Aid, “Loan Simulator” Methodology and Repayment Concepts, 2024. URL: studentaid.gov/loan-simulator.
  • 34 CFR § 685.202(b) – Interest capitalization rules for Direct Loans, 2024. URL: ecfr.gov.

All calculations strictly follow the formulas and regulatory sources cited above.

The Formula Explained

$$ r = \frac{\text{APR}}{12} \quad,\quad n = \text{years} \times 12 $$ $$ \text{AccruedInterestDuringGrace} = P \cdot \frac{\text{APR}}{12} \cdot m $$ $$ P_0 = \begin{cases} P + \text{AccruedInterestDuringGrace}, & \text{if capitalized} \\ P, & \text{otherwise} \end{cases} $$ $$ \text{Payment} = \begin{cases} \dfrac{P_0}{n}, & r = 0 \\ \dfrac{P_0 \cdot r}{1 - (1 + r)^{-n}}, & r \neq 0 \end{cases} $$ $$ \text{Extra Payment Scenario: amortize month-by-month with } \text{Payment}_\text{total} = \text{Payment} + \text{Extra} $$

Glossary of Variables

Symbol / FieldDefinition
PLoan amount (principal/face value).
APR (%)Nominal annual interest rate.
mMonths in in-school/grace period.
AccruedInterestDuringGraceInterest accrued before repayment begins.
P0Principal at repayment start (after optional capitalization).
rMonthly interest rate = APR / 12.
nNumber of scheduled payments (months) = years × 12.
PaymentMonthly scheduled payment from amortization formula.
ExtraOptional extra payment applied each month.
Total InterestSum of interest paid over the life of the loan.
Total PaidPrincipal + total interest.

Worked Example

How It Works: A Step-by-Step Example

  1. Inputs: P = $30,000; APR = 5.50%; Term = 10 years; m = 6 months; Capitalize = Yes; Extra = $50.
  2. Accrued interest during grace: 30,000 × 0.055/12 × 6 = $825; P0 = 30,825.
  3. Monthly rate: r = 0.055/12 ≈ 0.0045833; n = 120.
  4. Payment: P0 × r / (1 − (1 + r)^−120) ≈ $333.31.
  5. With Extra = $50, pay $383.31 monthly. Amortize month-by-month to get a shorter payoff time and less total interest.

Frequently Asked Questions (FAQ)

Do student loans accrue interest during school or grace periods?

Unsubsidized federal and most private loans accrue interest during in-school/grace periods. If you do not pay it, the interest may capitalize at repayment start, increasing principal.

What is interest capitalization and why does it matter?

Capitalization adds unpaid interest to your principal. Future interest is then calculated on the higher balance, increasing total cost and monthly payment.

Does this calculator handle zero-interest promos?

Yes. If APR is 0, the monthly payment becomes principal divided by the number of months.

Can I compare scenarios quickly?

Yes. Adjust inputs and the results update instantly. You can also add an extra monthly payment to see time and interest savings.

Are origination fees financed?

Federal origination fees are generally deducted from disbursement. Your payment is calculated on the principal (face value). The calculator shows your estimated net disbursement for transparency.

Does this support income-driven repayment (IDR)?

This tool focuses on fixed-payment amortization. For IDR, consult your servicer or the official Federal Student Aid Loan Simulator.

Amortization schedule (with extra payments if any)
Month Payment Interest Principal Balance
Enter your details to see the schedule.

Tool developed by Ugo Candido. Content verified by CalcDomain Editorial Team.
Last reviewed for accuracy on: .