Intent and Decision Guide
Use this calculator to compare your current mortgage structure against a refinance offer. The goal is to optimize total economics, not only monthly payment.
- Confirm break-even month is shorter than your expected home hold period.
- Compare fee-aware APR, not only headline APR.
- Check whether term extension lowers monthly payment but increases lifetime cost.
Edge and Stress Test Cases
| Case | Input Pattern | Watchpoint |
|---|---|---|
| Rate-drop refinance | $300,000 / 7.25% to 6.25% / 30y | Break-even and lifetime savings |
| Fee-heavy offer | $300,000 / 6.1% with high closing costs | Fee-aware APR may erase edge |
| Term-extension trap | Lower payment but 35-year total horizon | Lower monthly, higher long-run total |
Assumptions and Limits
- Model uses fixed-rate amortization with monthly compounding.
- Break-even assumes stable monthly savings and excludes future tax effects.
- Closing costs are treated as upfront unless explicitly rolled into principal.
- Fee-aware APR is an analytical estimate and not a regulatory APR disclosure.
- Rounding may create small differences vs lender statement-level ledgers.
- Always verify final terms against Loan Estimate and Closing Disclosure.
Sources and Review
| Source | Link |
|---|---|
| Freddie Mac PMMS | https://www.freddiemac.com/pmms |
| CFPB Loan Estimate guidance | https://www.consumerfinance.gov/owning-a-home/loan-estimate/ |
| CFPB refinance explainer | https://www.consumerfinance.gov/ask-cfpb/what-is-a-refinance-en-100/ |
Reviewer: Sam Park (Calculator QA and Content Operations).
Last reviewed: 2026-03-21 (Asia/Seoul).
Update Log
- 2026-03-21: Added refinance-specific comparison inputs (current vs new APR/term, closing costs).
- 2026-03-21: Applied debt engine v2 (full schedule, CSV export, extra payment, biweekly, fee-aware APR).
- 2026-03-21: Added break-even and lifetime savings outputs for refinance decisioning.
Who / How / Why
- Who: Internal calculator standard review based on Freddie Mac mortgage market data and CFPB refinance guidance.
- How: Compare current remaining loan with new refinance plan, then test acceleration strategies and fee-adjusted economics.
- Why: Prevent lower-payment offers that look attractive short term but lose on total lifetime cost.
Disclaimer
This is an educational estimate, not a binding lender quote. Final refinance costs, disclosures, and legal obligations depend on your lender and signed loan documents.
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Need a Tailored Refinance Scenario?
If you want a dedicated module for a specific refinance structure, send your case and we will include it in the next update cycle.
Contact Team