Fidamen

Auto Loan Balloon Payment Calculator with Bi-Weekly Payments

This calculator estimates periodic payments and balloon amounts for auto loans that include a lump sum due at the end of the term. It supports bi‑weekly, semi‑monthly and monthly payment schedules and two directions of calculation: compute the periodic payment when a balloon is specified, or compute the balloon amount when a periodic payment is specified.

Results are estimates intended for planning and comparison. Actual amounts may differ due to lender rounding rules, payment timing conventions, fees, insurance escrows, and local taxes. Use this tool to compare scenarios and verify figures with the lender before signing any loan documents.

Updated Nov 21, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record 7a07fd95a58b • Reviewed by Fidamen Standards Committee

Calculates the periodic payment amount when the loan includes a balloon due at the end of the term. Handles zero interest rate as a special case.

Inputs

Results

Updates as you type

Periodic payment

$418.41

Total number of payments

60

Balloon due at maturity

$5,000.00

Estimated total interest

$5,104.38

OutputValueUnit
Periodic payment$418.41USD
Total number of payments60payments
Balloon due at maturity$5,000.00USD
Estimated total interest$5,104.38USD
Primary result$418.41

Visualization

Methodology

We convert APR to a periodic rate using the selected frequency: periodic_rate = APR / 100 / payments_per_year, where payments_per_year is 26 for bi‑weekly, 24 for semi‑monthly, or 12 for monthly.

The loan present value equals principal plus any financed fees. For a loan with a balloon, the present value of the balloon is discounted to the same periodic basis. The periodic payment is solved from the standard annuity formula with the balloon present value subtracted from the financed amount.

Special handling: when the periodic interest rate is zero, the calculator uses linear division of principal (minus balloon present value) across payments to avoid division by zero.

Key takeaways

Use the default 'Compute periodic payment' method to find what bi‑weekly or monthly payment will be when a balloon is due at maturity.

Use the 'Compute balloon amount' method when you know the regular payment and want to find the required balloon that makes the loan balance reconcile.

Always confirm lender disclosures for exact payoff amounts, rounding, and additional fees.

F.A.Q.

Does this calculator reflect exact lender payoff schedules and late‑payment rules?

No. This tool produces standard mathematical estimates. Lenders may apply daily interest accrual, different compounding conventions, rounding to cents, or additional finance charges. Use results for planning and confirm the final payoff and disclosure with the lender.

Why is bi‑weekly different from semi‑monthly?

Bi‑weekly uses 26 equal payments per year (every two weeks). Semi‑monthly uses 24 payments (twice a month). These produce different periodic rates and schedules even when annual APR is identical.

What accuracy and computational standards were considered?

Calculations follow standard financial formulas for annuities and discounted lump sums. For numerical reliability and floating point behavior we reference established computing standards such as IEEE 754 for floating point representation, and guidance from NIST on numerical accuracy. Results are rounded to currency precision for display but underlying math may use double precision. For legal disclosures and regulatory compliance consult applicable financial regulations and your lender.

Can I use this for lease balloon or commercial loans?

The formulas model a loan with periodic fixed payments plus a lump-sum balloon at maturity. They do not include tax, insurance escrows, conditional residual values on leases, or specialized commercial adjustments. Adapt inputs to match your contract and verify with the issuer.

Sources & citations

Further resources

Versioning & Change Control

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

Record ID: 7a07fd95a58b

What changed (latest)

v1.0.0 • 2025-11-21 • 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 21, 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 • 2025-11-21 • 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: a839b89cc05d