Mortgage refinance calculator: savings and break-even
Compare two fixed-rate, fully amortizing loans with the same starting balance. Closing costs are paid upfront. Compares payments plus outstanding balances at the same holding horizon, without discounting.
Source parameters checked · version 2026-10-16 · review due 2027-01-16
Your inputs (USD)
Your estimate
Positive means lower modeled payments-plus-balance cost; negative favors keeping the current loan. No discounting or tax effects.
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Methodology and rounding
For each loan, monthly payment = P × r / (1 − (1+r)^−n), or P/n at zero interest. Step monthly interest and principal until payoff. At each horizon compare cumulative payments plus remaining balance; subtract the new-loan total and upfront fees from the old-loan total. The first non-negative month is reported, but savings can later reverse. Values are nominal; no discounting.
Worked example
Current monthly principal & interest: $1,863.93 · New monthly principal & interest: $1,719.72 · Monthly payment reduction: $144.21 · Upfront costs: $5,000.00 · Current loan balance at horizon: $213,972.80 · New loan balance at horizon: $210,470.33 · Holding horizon (months): 60 · First modeled cost-parity month: 25
Assumptions and exclusions
- Excludes cash-out, financed fees, variable rates, taxes, insurance, PMI, lender-specific terms and tax deductions.
- Include all incremental upfront costs, including any payoff penalty, in the fees input. No market-rate or fee estimates are supplied.
- Savings are nominal, not discounted. A lower payment alone does not establish lower economic cost.
Questions about this estimate
Does this cover every transaction or product?
No. This tool covers only its stated assumptions. Review the exclusions and official sources before using an estimate.
Are my inputs stored or included in shared links?
No. Calculations and comparisons stay in this tab. The calculator-link action copies the page address without financial inputs. Copy results places the visible figures on your own clipboard.
Official sources and review
Supported rates/formula, stated circumstances and rounding checked against the linked primary sources. Exclusions remain outside the model. This is a limited source check and tested estimate, not professional tax certification.
The calculator stops returning estimates after its review date until its rule version is updated. Report a correction.
Related tools
All available United States tools · Loan repayment · Compound growth
Guides for this calculation
Country guides for this calculator
Read the guide for your market; a general calculator retains its own assumptions.
Publisher, sources and review status
Published by Numbriv editorial team. Full jurisdiction/rule review is not recorded as complete. Existing formula tests do not certify every local rule.
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Explore United States calculators and coverage in USD. This calculator retains its stated jurisdiction and assumptions.