Fidamen

Business Loan Interest Calculator

This calculator helps business owners estimate periodic payment amounts, total interest, and payoff timing for term loans when using monthly, bi-weekly, or other recurring payment schedules. It supports estimating the effect of recurring extra payments applied each payment period.

Results are estimates intended for planning. Use the 'Standard amortization' method to see fixed-payment totals for the selected frequency, and use 'Accelerated payoff' to estimate how regular extra payments shorten the loan and lower interest. Always confirm numbers with your lender.

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

Governance

Record 3a2f2b06be31 • Reviewed by Fidamen Standards Committee

Computes the fixed periodic payment and totals assuming regular fixed payments for the chosen payment frequency and full term.

Inputs

Results

Updates as you type

Periodic payment (no extra)

$934.47

Estimated total interest (no extra)

$21,481.53

Estimated total amount paid (no extra)

$121,481.53

Number of payments

130

OutputValueUnit
Periodic payment (no extra)$934.47USD
Estimated total interest (no extra)$21,481.53USD
Estimated total amount paid (no extra)$121,481.53USD
Number of payments130payments
Primary result$934.47

Visualization

Methodology

The calculator converts the nominal annual interest rate (APR) into a periodic rate by dividing APR by the selected number of payments per year. For fixed-payment amortization the periodic payment is computed from the standard loan-payment formula: P = r * L / (1 - (1+r)^-N), where r is the periodic rate, L is principal, and N is total number of payments.

When recurring extra payments are included, the tool estimates the new payoff duration using the analytic formula for the number of payments required to amortize the remaining balance under the larger periodic payment. For zero-interest cases the calculator uses the linear payoff formula. There are safeguards and warnings when a recurring payment is too small to amortize interest.

Worked examples

Example: $100,000 principal, 8% APR, 5 years, bi-weekly payments (26/yr). The base periodic payment is computed for 130 payments. Adding a recurring $100 extra per payment reduces the number of payments and total interest — the calculator provides the estimated new payoff time and interest saved.

Example: For 0% APR the periodic payment is simply principal divided by total scheduled payments; recurring extras reduce the term linearly and the tool reports the direct payoff period.

F.A.Q.

Does bi-weekly always save interest compared to monthly?

Bi-weekly schedules often reduce interest because they increase the number of payments per year (26 payments vs 12) which can shorten principal faster. The precise savings depend on how your lender applies payments and whether they re-amortize or apply payments in a way that reduces principal sooner. This calculator assumes each payment is applied immediately to interest then principal.

Will extra payments always shorten the loan?

Yes if the extra payment is positive and at least large enough to cover the interest portion of a period. If the recurring payment is too small to cover per-period interest, the balance may not decline; the calculator flags that condition. For precise payoff dates when lenders apply payments irregularly, confirm with your lender.

Is this a legally binding payoff schedule?

No. This tool provides estimates for planning only. Actual lender statements, payment posting rules, and fees can change the schedule. Use the estimates as guidance and request an official payoff quote from your lender for exact figures.

How accurate are the calculations?

The formulas used are standard amortization formulas. Accuracy depends on correct inputs and the assumption that payments are applied each period without additional fees, prepayment penalties, or rounding rules. The tool includes accuracy caveats and warnings when inputs produce non-amortizing scenarios.

Sources & citations

Further resources

Versioning & Change Control

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

Record ID: 3a2f2b06be31

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: 17d2900b63a5