Fidamen

Auto Loan Balloon Calculator

This calculator covers common auto-loan scenarios that include a balloon payment at the end of the term. Use it to compute the periodic payment given an upfront loan and final balloon, compute the balloon given a payment, infer the loan principal from payment + balloon, or estimate remaining balance after a number of payments.

The tool assumes a nominal annual percentage rate (APR) converted to a periodic rate by dividing by the number of payments per year (for example, 12 for monthly). The balloon is treated as a lump sum payable at the final scheduled period.

Updated Nov 9, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record 18f11916f72e • Reviewed by Fidamen Standards Committee

Compute the fixed periodic payment when a lump-sum balloon is due at the end of the term.

Inputs

Advanced inputs

Common inputs

Balloon details (used by several methods)

Payment input (used by payment-based methods)

Payment and balloon (loan calculation)

Balance after N payments

Results

Updates as you type

Periodic payment (per period)

$303.90

OutputValueUnit
Periodic payment (per period)$303.90—
Primary result$303.90

Visualization

Methodology

Calculations use standard time-value-of-money formulas. Present value of the payment stream plus the discounted balloon equals the loan principal. Solve the algebraic form appropriate to the requested unknown.

Periodic interest rate r is APR / 100 / payments_per_year. Number of periods n is term_years * payments_per_year. Annuity factor for a level payment is (1 - (1 + r)^-n) / r. Present-value and future-value relationships follow established finance conventions.

Key takeaways

Use the mode selector to pick whether you want payment, balloon, loan principal, or outstanding balance calculations.

Provide nominal APR, payment frequency, term, and the known monetary values. Verify results against lender disclosures and consider rounding and fees.

Worked examples

If you borrow 20,000 with a 5% APR, 5-year term, monthly payments and a 5,000 balloon, the calculator returns the monthly payment required to amortize to that balloon.

If you make a fixed monthly payment and want to know the final balloon required for a given principal and term, switch to the balloon calculation mode and enter the payment amount.

F.A.Q.

Does this calculator use APR or nominal rate?

It expects a nominal APR value. It converts APR to a periodic rate by dividing by the number of payments per year. It does not compute finance charges under specific disclosure rules; use disclosed APR from your lender for regulatory comparisons.

What happens at zero interest rate?

The algebraic forms shown assume a positive interest rate. When the rate is zero, the periodic payment simplifies to (loan_amount - balloon_amount) divided by the number of periods. The tool provides guidance for zero-rate cases but numeric engines may require special handling to avoid division by zero.

Are results exact?

Results are based on standard closed-form formulas and floating-point arithmetic. Rounding, payment timing conventions, compounding differences, and lender-specific fees will affect real-world amounts. See accuracy caveats below.

Sources & citations

Further resources

External guidance

Versioning & Change Control

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

Record ID: 18f11916f72e

What changed (latest)

v1.0.0 • 2025-11-09 • 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 9, 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 • 2025-11-09 • 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: 69fb5ef03284