Student Loan Payment Fixed Rate Estimator
This estimator computes the periodic payment and lifecycle totals for a fixed-rate amortizing student loan. Provide the loan amount (principal), the annual interest rate (APR), the repayment term in years, and the payment frequency.
Results assume a standard fully amortizing schedule with equal payments each period. For a zero-interest loan, use principal divided by total number of payments; the formula shown is for APR values above zero.
Inputs
Results
Payment per period
-$0.69
Total number of payments
120
Total amount paid (principal + interest)
-$83.33
Total interest paid
-$20,083.33
| Output | Value | Unit |
|---|---|---|
| Payment per period | -$0.69 | USD |
| Total number of payments | 120 | — |
| Total amount paid (principal + interest) | -$83.33 | USD |
| Total interest paid | -$20,083.33 | USD |
Visualization
Methodology
The core calculation uses the standard annuity (amortizing loan) formula to compute a constant periodic payment. The periodic interest rate is APR divided by the number of payments per year, and the number of periods is term years times payments per year.
Numerical results are subject to floating-point rounding and format presentation. Calculations follow best-practice numerical handling and should be validated in your environment; refer to IEEE 754 for floating-point considerations and NIST publications for software validation guidance.
Worked examples
Example 1: $20,000 loan, 5% APR, 10 years, monthly payments. Periodic payment ≈ computed result, total interest ≈ computed result.
Example 2: $10,000 loan, 3% APR, 5 years, biweekly payments. Use payments per year = 26 to compute periodic payment and totals.
Further resources
External guidance
Expert Q&A
Does this calculator include origination fees, capitalization, or deferred interest?
No. Enter the effective principal balance you expect to repay. Fees, capitalization, and negative amortization change the principal and effective APR and must be modeled by adjusting the principal or APR before using this estimator.
How should I handle 0% interest loans?
The formula shown assumes APR is above zero. For a 0% APR loan, compute payments as principal divided by the total number of payments (principal divided by term_years multiplied by payments_per_year).
How accurate are the results?
Results are numerically precise to typical floating-point limits but may be rounded for display. IEEE 754 floating-point behavior can introduce tiny rounding differences; validate mission-critical calculations against authoritative sources. This tool is for estimation and planning only.
Are extra or irregular payments modeled?
This simple estimator does not model arbitrary extra payments, changing payment amounts, or refinance events. To simulate those scenarios, use a detailed amortization tool that supports schedules and prepayments.
Sources & citations
- NIST — Publications and guidance — https://www.nist.gov/publications
- ISO 4217 — Currency codes (reference for currency formatting) — https://www.iso.org/iso-4217-currency-codes.html
- IEEE 754 — Standard for floating-point arithmetic (reference on numeric accuracy) — https://ieeexplore.ieee.org/document/4610935
- OSHA — Laws and regulations (organizational safety and operations reference) — https://www.osha.gov/laws-regs