Fidamen

Personal Loan APR Calculator

This calculator compares standard monthly amortization, equal bi‑weekly amortization (26 payments/year), and the common accelerated bi‑weekly method (splitting the monthly payment in half). Enter the loan amount, the nominal annual interest rate (APR), and the loan term to see payments, total interest, and estimated payoff time.

Results use standard amortization formulas and assume no additional fees, no prepayments other than the calculated schedule, and that payments are applied to principal and interest on the period schedule shown.

Updated Nov 16, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record 293c8a692788 • Reviewed by Fidamen Standards Committee

Take the standard monthly payment, split it into two equal bi‑weekly payments (common consumer approach). Because there are 26 bi‑weekly payments in a year, this typically results in extra principal paid and a shorter payoff time.

Inputs

Results

Updates as you type

Bi‑weekly payment (monthly/2)

$99.01

Estimated years to payoff (accelerated)

—

Total interest (accelerated bi‑weekly)

—

OutputValueUnit
Bi‑weekly payment (monthly/2)$99.01—
Estimated years to payoff (accelerated)—years
Total interest (accelerated bi‑weekly)——
Primary result$99.01

Visualization

Methodology

Monthly results compute the fixed payment using the standard annuity formula: payment = P * r / (1 - (1 + r)^-n) where r is the periodic rate and n is the number of periods.

Bi‑weekly equal payments use 26 periods per year and the same annuity formula adjusted to the bi‑weekly periodic rate. The accelerated bi‑weekly method splits the monthly payment into two equal payments; because there are 26 bi‑weekly payments per year this typically results in extra principal paid and a shorter term.

Calculations use floating‑point arithmetic consistent with IEEE 754 conventions for numeric operations. Financial rounding is shown in display but intermediate calculations keep higher precision to reduce cumulative rounding error.

Key takeaways

This advanced calculator provides side‑by‑side estimates for monthly, bi‑weekly, and accelerated bi‑weekly payment schedules using standard amortization mathematics.

Use the results for planning and comparisons, and rely on lender disclosures for legally binding APR and payment terms.

Worked examples

Example 1: $10,000 principal, 7% APR, 5 years. Compare monthly payment vs accelerated bi‑weekly: accelerated approach generally reduces total interest and shortens payoff.

Example 2: $25,000 principal, 5.5% APR, 7 years. Equal bi‑weekly schedule with 26 payments/yr yields different periodic payment and an equivalent effective annual rate compounded bi‑weekly.

F.A.Q.

Does this calculator show the regulatory APR?

No. The input 'annual interest rate (nominal APR %)' is treated as the nominal annual rate. Regulatory APR can include certain fees and differing disclosure rules; this tool shows nominal rates, effective periodic rates, payments and totals. For official APR disclosures consult your lender or the consumer finance disclosure you received.

Why do accelerated bi‑weekly payments pay the loan off faster?

Splitting the monthly payment into two bi‑weekly payments results in 26 payments per year (equivalent to 13 full monthly payments), which increases annual principal reduction relative to 12 monthly payments and shortens the amortization period.

How accurate are the numbers?

Results use standard amortization formulas and double‑precision arithmetic per IEEE 754. Displayed results are rounded for readability. Differences may occur due to lender rounding rules, day count conventions, fees, or payment application timing.

How should I use these outputs when shopping for loans?

Use the comparison to understand how payment frequency affects total interest and payoff time. Always compare lender disclosures (including any fees) and the legally provided APR. This calculator is for estimation and planning, not a substitute for lender disclosures.

Sources & citations

Further resources

Versioning & Change Control

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

Record ID: 293c8a692788

What changed (latest)

v1.0.0 • 2025-11-16 • 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 16, 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 • 2025-11-16 • 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: c996b7e13f5c