Fidamen

Student Loan APR Calculator with Bi-Weekly Payments

This calculator estimates the periodic payment, total paid, total interest, number of payments, and the effective annual rate for a student loan given a nominal APR and a payment frequency (monthly, bi‑weekly, or weekly). It supports adding a fixed extra payment each period to show its impact on interest and payoff time.

Use this tool for planning and comparison. Results are estimates produced by standard amortization formulas and should be compared to your lender's schedule or statement for final values.

Updated Nov 8, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record e632b7e569ea • Reviewed by Fidamen Standards Committee

Inputs

Results

Updates as you type

Payment per period

—

Total amount paid

—

Total interest paid

—

Number of payments

260

Effective annual rate (EAR)

512.21%

OutputValueUnit
Payment per period—USD
Total amount paid—USD
Total interest paid—USD
Number of payments260—
Effective annual rate (EAR)512.21%%
Primary result—

Visualization

Methodology

Calculations use the standard amortization formula for fixed-rate installment loans applied to the selected payment frequency (periodic interest rate = nominal APR / frequency).

When APR is zero, the calculator uses a simple division of principal across the number of scheduled payments. For nonzero APR the periodic payment is computed with a geometric annuity formula.

Effective annual rate (EAR) is derived from compounding the periodic rate over the year: EAR = (1 + r_period)^(periods_per_year) − 1.

Key takeaways

This estimator applies standard fixed‑rate amortization formulas to the chosen payment frequency and includes optional per‑period extra payments.

Use lender statements for final billing values. The tool follows best practices for display of inputs and derived metrics and includes references to measurement and software standards for transparency.

F.A.Q.

Does switching to bi‑weekly payments always save interest?

Bi‑weekly schedules create more frequent compounding intervals compared with monthly schedules and can reduce interest if the payment structure increases the amount applied to principal sooner. Savings depend on whether your lender applies payments immediately and whether you actually make the extra amount required to match a true bi‑weekly plan.

Is the calculator precise for legal or billing disputes?

No. This calculator produces estimates based on standard formulas. For legal, tax, or billing disputes rely on official loan statements and lender amortization schedules. The tool includes accuracy caveats and is not a substitute for lender disclosures.

What if my loan has fees, changing rates, or capitalization?

This tool assumes a fixed nominal APR and fixed periodic payments. Loans with origination fees, variable rates, capitalization events, grace periods, or income‑driven repayment plans require specialized modeling and are not fully supported here.

Why is effective annual rate (EAR) different from APR?

APR is typically a nominal annual rate that does not reflect intra‑year compounding. EAR accounts for compounding within the year and therefore may be higher than the nominal APR for the same rate when payments compound multiple times each year.

Sources & citations

Further resources

External guidance

Versioning & Change Control

Audit record (versions, QA runs, reviewer sign-off, and evidence).

Record ID: e632b7e569ea

What changed (latest)

v1.0.0 • 2025-11-08 • MINOR

Initial publication and governance baseline.

Why: Published with reviewed formulas, unit definitions, and UX controls.

Public QA status

PASS — golden 25 + edge 120

Last run: 2026-01-23 • Run: golden-edge-2026-01-23

Engine

v1.0.0

Data

Baseline (no external datasets)

Content

v1.0.0

UI

v1.0.0

Governance

Last updated: Nov 8, 2025

Reviewed by: Fidamen Standards Committee (Review board)

Credentials: Internal QA

Risk level: low

Reviewer profile (entity)

Fidamen Standards Committee

Review board

Internal QA

Entity ID: https://fidamen.com/reviewers/fidamen-standards-committee#person

Semantic versioning

  • MAJOR: Calculation outputs can change for the same inputs (formula, rounding policy, assumptions).
  • MINOR: New features or fields that do not change existing outputs for the same inputs.
  • PATCH: Bug fixes, copy edits, or accessibility changes that do not change intended outputs except for previously incorrect cases.

Review protocol

  • Verify formulas and unit definitions against primary standards or datasets.
  • Run golden-case regression suite and edge-case suite.
  • Record reviewer sign-off with credentials and scope.
  • Document assumptions, limitations, and jurisdiction applicability.

Assumptions & limitations

  • Uses exact unit definitions from the Fidamen conversion library.
  • Internal calculations use double precision; display rounding follows the unit's configured decimal places.
  • Not a substitute for calibrated instruments in regulated contexts.
  • Jurisdiction-specific rules may require official guidance.

Change log

v1.0.0 • 2025-11-08 • MINOR

Initial publication and governance baseline.

Why: Published with reviewed formulas, unit definitions, and UX controls.

Areas: engine, content, ui • Reviewer: Fidamen Standards Committee • Entry ID: 0391704241fd