Complete guide
Refinance Calculator: formula, worked example and interpretation
Compare an existing mortgage with a proposed refinance and calculate the closing-cost break-even point. Enter the known values and the result updates instantly with an auditable breakdown.
What the Refinance Calculator answers
Compare an existing mortgage with a proposed refinance and calculate the closing-cost break-even point.
Use the breakdown to compare the result with the source values before making a decision.
Formula and variables
The calculation uses break-even=closing costs/(old payment−new payment). Every variable comes directly from a labeled field.
break-even=closing costs/(old payment−new payment)Worked example
A $300,000 balance is priced under the current and proposed terms before dividing costs by monthly savings.
Changing any field recalculates the result immediately, so nearby scenarios can be compared without reloading the page.
How to use the result
Treat the result as a planning value and compare it with the detailed rows shown beside it.
Keep units and time periods consistent. Use the share or PDF action to preserve the exact assumptions.
Assumptions and scope
A lower payment can still extend debt and increase lifetime cost. Taxes, escrow, points and cash-out require separate inputs.
The calculator exposes its assumptions instead of filling missing facts with hidden estimates.
Accuracy checks
Confirm the units, dates, rates and source figures before relying on the output.
Round only the displayed answer; Calculator24 keeps full JavaScript precision for intermediate arithmetic and exported values.
Input and output checklist
| Item | What to enter or review |
|---|---|
| Inputs | Current balance ($), Current APR (%), Current years remaining, New APR (%), New term (years), Closing costs ($) |
| Equation | break-even=closing costs/(old payment−new payment) |
| Example | A $300,000 balance is priced under the current and proposed terms before dividing costs by monthly savings. |
| Limit | A lower payment can still extend debt and increase lifetime cost. Taxes, escrow, points and cash-out require separate inputs. |
Frequently asked questions
What does this Refinance Calculator calculate?
Compare an existing mortgage with a proposed refinance and calculate the closing-cost break-even point.
Which formula does it use?
break-even=closing costs/(old payment−new payment)
Does the result update while I type?
Yes. Valid changes recalculate after a short delay and the previous result is not substituted for invalid input.
Which assumptions should I check?
Check units, rates, dates and every source value shown in the form.
Is the result exact?
A lower payment can still extend debt and increase lifetime cost. Taxes, escrow, points and cash-out require separate inputs.
Can I save or share the calculation?
Yes. Copy, Share, WhatsApp, PDF/Print, CSV, comparison and parameterized-link actions are available.
What to keep in mind
A lower payment can still extend debt and increase lifetime cost. Taxes, escrow, points and cash-out require separate inputs.
Results display up to 8 decimal places; exported numbers preserve calculation precision. This is a calculation summary, not an official certificate.