Practical guide
Understanding mortgage refinance check — two-scenario comparison
Everyday editorial team · GEOINNOVATION CO., LTD · Published · Updated
What this calculation is for
Refinancing replaces a debt with new terms. A useful comparison includes closing costs, the remaining old term and the proposed new term, not just the interest rate. A smaller monthly payment can come from extending the debt rather than reducing total cost.
How the method works
The tool calculates current and proposed fixed-rate principal-and-interest payments. In this model, entered refinance costs are financed in the new balance. It also shows a simple fee-to-payment-savings break-even measure, which is a cash-flow heuristic rather than a full investment valuation.
A worked example
A $3,000 cost and a $100 monthly reduction imply a simple 30-month break-even. If you expect to sell or repay in 12 months, that reduction alone would not recover the cost over your expected holding period.
Assumptions and real-world differences
Compare total interest and remaining balances as well as payments. The simplified break-even omits tax effects, discounting, payoff penalties and changes to insurance or escrow. Financing the costs adds interest beyond their face amount.
Building two independent scenarios
Scenario A and Scenario B each have a complete set of inputs for this mortgage refinance check calculation. Change several inputs in B when comparing genuinely different plans, then inspect the B-minus-A headline difference and the detailed rows. When multiple inputs change, the total difference cannot be attributed to just one of them.
Reproduce this tool’s example
These fixed example inputs are independent of edits you make above. Enter them in this tool to reproduce the result, then replace them with your own assumptions.
- Scenario A — Remaining loan balance
- 240,000 $
- Scenario A — Current APR
- 7 %
- Scenario A — New APR
- 6.25 %
- Scenario A — Current remaining term
- 24 years
- Scenario A — New loan term
- 20 years
- Scenario A — Refinance closing costs
- 4,500 $
- Scenario B — Remaining loan balance
- 300,000 $
- Scenario B — Current APR
- 7 %
- Scenario B — New APR
- 6.25 %
- Scenario B — Current remaining term
- 24 years
- Scenario B — New loan term
- 20 years
- Scenario B — Refinance closing costs
- 4,500 $
Scenario B result: $-72.4
Scenario A: $-64.5. Monthly payment change.
- Scenario A main result: $-64.5
- Scenario B main result: $-72.4
- Numeric difference (B − A), in result units: -7.9
Frequently asked questions
- Is a lower rate always worthwhile?
- No. Fees, term changes and your time horizon can outweigh the rate reduction.
- Does break-even prove I should refinance?
- No. It is one simplified measure, not a recommendation or a net-present-value analysis.
- Why is this different from the one-factor comparison?
- The one-factor tool changes only remaining loan balance. This version lets all model inputs differ, so it is more flexible but does not isolate the effect of any single change.