Fidamen

Business Loan Amortization Calculator with Extra Payments

This calculator helps business borrowers understand how extra recurring payments or a single lump-sum principal paydown change the amortization schedule: it shows revised payoff period, total interest paid, and estimated interest savings compared with the original schedule.

Use the three modes for common scenarios: standard amortization (no extras), recurring extra payment applied to each scheduled payment, or a one-time lump-sum reduction applied at a chosen payment. Review the accuracy caveats below before relying on precise cent-level amounts.

Updated Nov 6, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record e5279ae940a7 • Reviewed by Fidamen Standards Committee

Apply a fixed extra amount to each scheduled payment (optionally beginning after a chosen payment). Computes shortened payoff and interest savings.

Inputs

Advanced inputs

Recurring extra payment options

Lump-sum options

Results

Updates as you type

Payment with recurring extra

$2,938.70

Number of payments to payoff

—

Years to payoff

—

Interest saved

—

OutputValueUnit
Payment with recurring extra$2,938.70—
Number of payments to payoff—payments
Years to payoff—years
Interest saved—USD
Primary result$2,938.70

Visualization

Methodology

All methods assume a fixed nominal annual interest rate, constant payment amount for the scheduled payment, and that extra payments are applied directly to principal at the time of each payment.

Calculations use standard annuity formulas: the periodic rate is the annual rate divided by payments per year; the scheduled payment solves the annuity present value equation. For recurring extras and lump sums the remaining number of payments is solved from the annuity equation algebraically.

This tool does not model variable rates, grace periods, fees, escrow, prepayment penalties, compounding conventions other than per-period, or lender-specific allocation rules. For those cases, request an official amortization schedule from your lender.

Worked examples

Example: $200,000 loan, 6% annual, 10-year term, monthly payments. Adding $200 extra per month shows faster payoff and interest saved compared to the original schedule.

Example: Same loan, $10,000 lump sum after 12 payments reduces principal and shortens remaining term; results assume scheduled payments stay constant after the lump sum.

F.A.Q.

Does the calculator account for prepayment penalties or fees?

No. The model does not include prepayment penalties, origination fees, or other lender-specific charges. If your loan has such terms, obtain a lender-provided schedule or adjust results manually to include those costs.

What if the interest rate is zero?

At a zero interest rate the scheduled payment formula simplifies to principal divided by number of payments. Some algebraic expressions in this tool assume a positive rate; results for a zero rate are handled conceptually but verify output in that edge case.

Are results exact to the cent?

Results are algorithmic estimates using closed-form annuity equations and algebraic solutions for remaining periods. Small rounding rules, day-count conventions, or lender allocation rules can shift cents and payment counts; treat outputs as accurate estimates, not legal or loan-accounting statements.

Can I enter weekly or custom payment frequencies?

You may select common frequencies (monthly, quarterly, annual). For other frequencies, convert payments_per_year accordingly (for example, 52 for weekly) but verify with your lender how interest is compounded and payments are applied.

Sources & citations

Further resources

External guidance

Versioning & Change Control

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

Record ID: e5279ae940a7

What changed (latest)

v1.0.0 • 2025-11-06 • 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 6, 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 • 2025-11-06 • 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: 2012962cdcf1