Intent and Decision Guide
- Use conservative affordability for offer planning.
- Stress test APR before locking.
- Keep back-end DTI in a safe operating zone.
Edge and Stress Test Cases
| Case | Input Pattern | Watchpoint |
|---|---|---|
| Rate shock | APR 6% to 8% | Purchasing power drop |
| Debt increase | Debts +$300/mo | Back-end DTI pressure |
| Low down payment | Down under 20% | PMI drag and max price impact |
Assumptions and Limits
- Fixed-rate monthly amortization assumption.
- Tax and insurance are estimated percentages.
- PMI estimate is simplified and lender-specific.
- Approval depends on full underwriting factors.
- Rounding differences may occur.
Transparency Block (Who / How / Why + Update Log)
Who: Homebuyers planning budget discipline before pre-approval.
How: Converts income and debt profile into affordability envelope under explicit assumptions.
Why: Prevents over-borrowing by anchoring to sustainable monthly cash flow.
Update Log
- 2026-03-21: Added debt optimization v2 and full amortization schedule with CSV export.
- 2026-03-21: Added explicit edge/stress cases and transparency block.
- 2026-03-21: Added route-level GA events for calculator start/complete and CTA click.
Disclaimer: Educational estimate only. Final terms and approvals depend on lender underwriting and signed disclosures.
Sources and Review
Reviewer: Sam Park (Calculator QA and Content Operations).
Last reviewed: 2026-03-21 (Asia/Seoul).
Related Core20 Tools
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