Fidamen

Mortgage Balloon Calculator

This calculator computes the periodic amortizing payment based on a chosen amortization schedule and the remaining principal (the balloon) due at a specified shorter term. It is intended for common balloon mortgage structures where regular payments are calculated as if the loan amortizes over a longer schedule but a lump-sum balance is due earlier.

Use the inputs to model scenarios (monthly, quarterly, annual payments). Ensure the balloon term is less than or equal to the amortization period. For zero-rate cases or extreme edge inputs see the accuracy notes below.

Updated Nov 11, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record a85620e03351 • Reviewed by Fidamen Standards Committee

Inputs

Results

Updates as you type

Periodic payment

-$3.47

Balloon payment due at term

$365,443.00

Total payments made before balloon

-$291.67

Interest paid before balloon

$65,151.33

OutputValueUnit
Periodic payment-$3.47USD
Balloon payment due at term$365,443.00USD
Total payments made before balloon-$291.67USD
Interest paid before balloon$65,151.33USD
Primary result-$3.47

Visualization

Methodology

Calculations use standard time-value-of-money formulas: fixed-rate annuity payment for an amortization schedule and the outstanding principal formula for remaining balance after k payments. The payment formula is the canonical amortizing loan formula, and the remaining principal is derived from the amortization schedule.

For numerical robustness we follow best-practice guidance on floating-point computation and software quality: implementers should adhere to IEEE 754 for binary floating-point behavior, ISO quality management practices (ISO 9001) for verification, and NIST recommendations for secure, auditable software development.

This tool provides model outputs for planning and comparison only. It is not a binding loan offer. Always confirm final figures with your lender and review contract terms for prepayment, taxes, insurance, fees, or adjustable-rate clauses that are not modeled here.

Worked examples

Example: $300,000 principal, 5% annual rate, 30-year amortization, balloon at 7 years, monthly payments: periodic payment ≈ computed payment, balloon ≈ remaining principal due at year 7. Use calculator inputs to view exact figures.

Zero interest example: With 0% interest, payment equals principal divided by total amortization payments; the remaining principal after k payments equals principal minus payments already applied.

F.A.Q.

What is a balloon payment?

A balloon payment is the remaining principal balance due at the end of a shorter term when the payment schedule was calculated on a longer amortization. Borrowers make regular payments that do not fully amortize the loan; the unpaid balance is due as a lump sum at the balloon date.

Can I use any payment frequency?

Yes. Set payments per year to match your contract (12 for monthly, 4 for quarterly, 1 for annual, 26 for biweekly, etc.). The calculator converts the annual rate to the periodic rate using the selected payments per year.

What about zero or extremely low interest rates?

When the periodic interest rate is zero, formulas that divide by the rate are undefined. In that case the calculator should switch to linear calculations: payment = principal / (amortization_years * payments_per_year) and outstanding principal reduces linearly. Always verify zero-rate scenarios manually or with lender statements.

How accurate are these results?

Results follow standard amortization mathematics and typical floating-point arithmetic. Small rounding differences can occur due to implementation (binary floating point, rounding to cents). For regulatory reporting or contractual figures, reconcile with lender-provided amortization schedules. See accuracy and limits below.

Sources & citations

Further resources

Versioning & Change Control

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

Record ID: a85620e03351

What changed (latest)

v1.0.0 • 2025-11-11 • 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 11, 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 • 2025-11-11 • 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: 4c0b5addde40