Mortgage Refinance Calculator
Compare your current home loan with a new refinance loan. Calculate monthly savings, total interest saved, and exact break-even time in months.
How to Calculate Mortgage Refinance Savings
Refinancing replaces an existing mortgage with a new loan having different terms, interest rates, or balances. To determine if refinancing is advantageous, you must evaluate three core financial metrics:
For deeper analysis and related planning, you can also explore our EMI Calculator and Simple Interest Calculator.
- Monthly Payment Impact: The difference between your current monthly principal and interest payment ($M_{\text{old}}$) and your new monthly payment ($M_{\text{new}}$).
- The Break-Even Horizon: The number of months required for cumulative monthly savings to recover the upfront closing costs.
- Lifetime Net Interest Difference: The total interest remaining on your old loan minus total interest paid on the new loan minus all loan fees.
Standard Mortgage Amortization Formula
Both current and refinance monthly payments are calculated using standard banking amortization:
Where P is the loan principal, r is the monthly interest rate (annual rate divided by 12), and n is the total number of monthly payment installments (years × 12).
Understanding the Break-Even Horizon
Closing costs for a mortgage refinance typically range from 2% to 4% of the loan amount (typically $3,000 to $6,000). Common closing fees include:
- Lender Origination and Underwriting fees ($1,000 to $2,000)
- Home Appraisal inspection ($400 to $700)
- Title Search and Title Insurance ($700 to $1,500)
- Recording and State Transfer taxes ($200 to $600)
The mathematical break-even formula is:
If you plan to sell the property or move before reaching your break-even month, refinancing will result in a net financial loss regardless of the lower interest rate.
When Refinancing Makes Sense
Frequently Asked Questions
What is the mortgage refinance break-even period?
The break-even period is the number of months required for your monthly mortgage payment savings to equal the upfront closing costs of the refinance. For example, if closing costs are $4,000 and your monthly payment drops by $200, your break-even point is 20 months ($4,000 ÷ $200).
How much should mortgage rates drop to justify refinancing?
Financial advisors historically recommend refinancing when current market mortgage rates are at least 0.75% to 1.0% lower than your existing rate, provided you plan to stay in the home longer than the break-even period.
Should I roll closing costs into the new loan balance?
Rolling closing costs into your new mortgage avoids out-of-pocket cash requirements, but increases your principal loan balance and results in paying interest on those fees over the remaining term of the loan.
Financial Disclaimer: This calculator provides mathematical estimates based on fixed-rate amortization equations. It does not account for local property tax re-assessments, homeowners insurance adjustments, or adjustable-rate mortgage (ARM) reset caps. Consult a licensed mortgage professional or certified financial advisor before executing loan documents.