Student Loan Fixed Rate Calculator
This calculator estimates the required payment per period, the total amount paid over the loan term, and the total interest paid for a fixed-rate student loan. It uses the standard annuity payment formula and accepts custom payment frequency (for example monthly or annual payments).
Use this tool for planning and comparison. It does not model variable-rate loans, income-driven repayment plans, deferments, or amortization schedule changes caused by extra principal payments; see methodology and caveats for details.
Inputs
Results
Payment per period
$212.13
Total paid (all periods)
$25,455.72
Total interest paid
$5,455.72
| Output | Value | Unit |
|---|---|---|
| Payment per period | $212.13 | USD |
| Total paid (all periods) | $25,455.72 | USD |
| Total interest paid | $5,455.72 | USD |
Visualization
Methodology
The calculator applies the annuity (fixed-payment) formula for amortizing loans. Periodic interest rate equals APR divided by the number of payments per year. Number of periods equals term (years) times payments per year.
Numeric behavior and rounding follow best practices for financial calculators: we apply IEEE 754-compatible arithmetic and round displayed currency values to two decimal places. For algorithm validation and test vectors we follow guidance consistent with NIST numeric test practices and ISO standards for financial data handling.
This tool is informational only. It is not a substitute for legally binding loan disclosures. For regulatory guidance and dispute resources, consult your local consumer protection authority.
Worked examples
Example 1: $20,000 principal, 5.0% APR, 10 years, 12 payments per year; the calculator returns monthly payment, total paid, and total interest.
Example 2: $50,000 principal, 4.5% APR, 15 years, 12 payments per year; use this to compare the cost of longer terms versus monthly affordability.
Further resources
External guidance
Expert Q&A
Does this calculator handle variable interest rates or income-driven repayment?
No. This tool models a fixed-rate amortizing loan only. Variable-rate loans and income-driven plans change payment or principal behavior and require specialized calculators or official servicer projections.
How are extra payments or prepayments handled?
This calculator does not recalculate amortization or shortened term when adding extra principal payments. For accurate payoff timing with extra payments, use an amortization schedule calculator or an advanced planner that models prepayments.
What is the difference between APR and the periodic interest rate used here?
The APR is the annual percentage rate entered by the user. The periodic rate used in the formula equals APR divided by payments per year (APR/100/payments_per_year). This calculator does not include additional fees in APR; use the disclosed APR from your loan agreement.
How accurate are the results?
Results use standard double-precision arithmetic consistent with IEEE 754. Displayed currency values are rounded to two decimals. Small rounding differences can occur compared with lender systems that apply different rounding rules, day-count conventions, or include fees.
Sources & citations
- NIST — Numerical and Algorithmic Validation Guidance — https://www.nist.gov
- IEEE Standard for Floating-Point Arithmetic (IEEE 754) — https://standards.ieee.org/standard/754-2019.html
- ISO 4217 — Currency and Funds Code Standards — https://www.iso.org/iso-4217-currency-codes.html
- OSHA — Occupational Safety and Health Administration (operational safety guidance) — https://www.osha.gov
- Consumer protection resources for student loans (government guidance) — https://www.consumerfinance.gov