Interactive Mortgage
Optimization Visualizers
High-performance visual tools designed to help you analyze mortgage options. Model your recast savings, compare HELOC blended rates, and map out your PMI removal timeline in real time.
Mortgage Recast
Model how a principal lump sum reduces your required monthly payment and lifetime interest cost.
HELOC vs. Refi
Compare the blended interest rate of a second mortgage against resetting your first mortgage.
PMI Removal
Project when your loan-to-value (LTV) ratio reaches the 80% threshold to eliminate mortgage insurance.
Sell vs. Rent
Evaluate whether to convert your departing home into a rental property or sell it for capital gains.
Interactive Recast Simulator
Test the recast sandbox model to visualize how a lump sum principal payment impacts your monthly cash flow and interest curves.
Interactive Recast Sandbox
Drag the sliders to see how a lump sum recast bends your amortization curve.
New Monthly Payment
Monthly Cash Flow Saved
High-speed, client-side mortgage modeling.
The Mortgage Curve is an educational utility. All calculations are executed locally in your browser memory to ensure maximum performance, instant visual updates, and complete data privacy.
Calculations run directly inside your browser. No mortgage data or sensitive numbers are sent or saved to external databases.
Mortgage inputs are synchronized into the URL query parameters in real time. Simply share or bookmark the link to save your exact scenario.
Amortization lines render instantly on your local CPU without network round-trips, allowing fluid slider adjustments.
Visualizers feature printable CSS stylesheets for physical checksheets and standard CSV exports for raw mortgage data analysis.
Mortgage Strategy & Payoff FAQs
Learn more about recasting, blended interest rates, and PMI elimination strategies.
How do I decide between a Mortgage Recast, a HELOC, and a Refinance?
Your decision should focus on your current interest rate, capital requirements, and cash flow objectives:
- Choose a Recast if you have a low interest rate, cash on hand (e.g., from a house sale or bonus), and want to permanently lower your required monthly payments.
- Choose a HELOC if you need to access your home equity for expenses but want to preserve your low first-mortgage rate.
- Choose a Refinance only if current market rates are lower than your existing rate, or if you need to refinance out of an FHA loan to eliminate permanent mortgage insurance.
What is a mortgage recast and how does it save money?
A mortgage recast allows you to make a lump-sum principal payment toward your existing mortgage balance. The lender then recalculates (re-amortizes) your remaining balance over the original remaining term, permanently lowering your required monthly payment.
Unlike refinancing, a recast preserves your existing fixed interest rate and term, avoiding expensive closing costs. It saves money by reducing the principal balance that accrues interest over time, while immediately improving monthly cash flow.
What is a "blended interest rate" and why is it important when tapping home equity?
A blended rate is the true weighted average interest rate of your combined housing debt (first mortgage plus any secondary loans like HELOCs).
For example, if you have a $300,000 first mortgage at 3% and take a $100,000 HELOC at 8%, your blended interest rate is 4.25%—not 8%. Calculating this true weighted cost helps you evaluate if taking a HELOC is cheaper than a full cash-out refinance, which would force your entire first mortgage balance up to current market rates.
How is a Private Mortgage Insurance (PMI) removal timeline projected?
Under the Homeowners Protection Act, lenders must automatically terminate Private Mortgage Insurance (PMI) on conventional loans when the principal balance reaches 78% of the original purchase price, provided payments are current. Homeowners can formally request removal at 80% LTV.
Our PMI Removal calculator maps out the exact month you will reach these equity levels. It evaluates your standard amortization schedule, allows you to model home price appreciation rates, and calculates the direct return on investment (ROI) of making extra principal payments to drop PMI early.
Can FHA or VA loans use mortgage recasting or standard PMI removal?
FHA and VA loans have distinct federal rules that differ from conventional mortgages:
- Recasting: Government-backed FHA, VA, and USDA loans generally do not support recasting. This option is typically restricted to conventional conforming loans.
- Mortgage Insurance: Private Mortgage Insurance (PMI) on conventional loans can be removed at 80% LTV. FHA loans carry Mortgage Insurance Premiums (MIP) that typically last for the entire life of the loan. To eliminate FHA MIP, borrowers must refinance into a conventional loan once they reach 20% equity.
Is it mathematically better to pay down my mortgage principal or invest in the stock market?
Paying down mortgage principal provides a guaranteed, tax-free return equal to your mortgage interest rate. For example, paying down a 6.5% mortgage balance is equivalent to earning a guaranteed 6.5% return.
If your mortgage rate is very low (e.g., 3%), you may earn a higher net return by investing in diversified market index funds. However, in higher interest rate environments, prepaying principal offers an attractive risk-adjusted, guaranteed return that is difficult to replicate in the stock market.