Fidamen

Motorcycle Loan Interest Calculator with Extra Payments

This calculator estimates periodic payments, payoff time and total interest for a motorcycle loan when you add a recurring extra payment each period. Use it to compare the effect of extra payments on interest savings and earlier payoff.

Results assume interest compounds at the payment frequency and extra payments are applied each payment period toward principal. This tool provides estimates for planning purposes only and is not a loan offer.

Updated Nov 30, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record 564991aff0c8 • Reviewed by Fidamen Standards Committee

Inputs

Results

Updates as you type

Periodic payment (no extra)

$195.66

Periodic payment (with extra)

$195.66

Number of payment periods to payoff

60

Total amount paid

—

Total interest paid

—

OutputValueUnit
Periodic payment (no extra)$195.66USD
Periodic payment (with extra)$195.66USD
Number of payment periods to payoff60periods
Total amount paid—USD
Total interest paid—USD
Primary result$195.66

Visualization

Methodology

We compute the standard annuity payment for a fixed-rate loan: when APR is above zero, periodic rate r = APR divided by 100 divided by payments_per_year and payment = P × r / (1 - (1+r)^-n) where n = years × payments_per_year. For zero APR, payment equals principal divided by n.

If you add a constant extra payment each period, the effective periodic payment increases and payoff occurs sooner. For a nonzero rate we use the closed-form logarithmic solution for the number of periods remaining given the increased payment. For zero interest we use linear division of principal by payment.

All numeric computations follow common financial formulas; results are rounded for presentation. See citations for standards and accuracy notes.

F.A.Q.

Does the calculator handle one-time extra payments?

This version assumes a constant recurring extra payment each period. One-time extra payments or variable schedules require an amortization simulation. Use the recurring extra value to approximate repeated contributions.

What if APR is 0%?

When APR is zero the formulas simplify: periodic payment = principal ÷ total periods and periods to payoff = principal ÷ (periodic payment + extra). The calculator handles APR = 0 as a special case to avoid division by zero.

Are results exact for all edge cases?

Results are mathematically consistent with fixed-rate amortization formulas. Rounding, payment timing conventions, lender fees, day-count conventions, and compounding differences used by lenders may cause small differences. Always verify with your loan agreement or lender.

Can I use different payment frequencies?

Yes. Set payments per year to match the frequency (for example 12 for monthly, 26 for biweekly, 52 for weekly). The calculator assumes the interest rate provided is the nominal APR and is converted to the periodic rate by dividing by payments per year.

Sources & citations

Further resources

External guidance

Versioning & Change Control

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

Record ID: 564991aff0c8

What changed (latest)

v1.0.0 • 2025-11-30 • 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 30, 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 • 2025-11-30 • 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: ad00877c330e