Methodology

StayOrRefi Method v1.0, published October 4, 2026.

What the calculator does

The Stay or Refi Calculator takes the balance, current rate, years remaining, new rate, new term, estimated closing costs, and expected stay that you enter. It amortizes both loans with the standard fixed-rate formula, payment = balance x r / (1 - (1 + r)^-n), where r is the monthly rate and n is the number of payments. Break-even month is closing costs divided by the monthly payment saving, rounded up. Net over stay compares interest paid during your stay horizon under each loan, with closing costs charged to the new loan. Lifetime interest runs both loans to their full terms so a term restart is visible instead of hidden.

Assumptions, printed rather than buried

• Fixed rates for the full term. Adjustable loans are handled by guide analysis, not this tool.
• No cash out, no prepayment, no late payments, no rate buydown beyond what you include in closing costs.
• Taxes, insurance, and escrow excluded, because the lender does not set what you owe for them.
• No tax effects. Mortgage interest deductibility depends on your situation; a tax professional can model it.

Sources

• Freddie Mac Primary Mortgage Market Survey for national rate context, updated from the official weekly release.
• Consumer Financial Protection Bureau consumer guidance and the Loan Estimate format for closing cost categories.
• Fannie Mae and Freddie Mac program publications, plus official FHA and VA pages, where loan-type rules are described.

Review process

Each page passes three checks before publication: source verification (every figure traces to a named source and date), formula test (calculator outputs are compared against hand-worked amortization examples), and editorial review (estimates labelled, no lender recommendations, no rate predictions). Dates on pages distinguish when content was reviewed, when a source figure was verified, and when a figure changed; cosmetic edits do not move a visible date.

What this site will not do

• No lender rankings, no best-lender lists, no loan offers, and no rate predictions.
• No invented statistics. If a figure cannot be traced, it is not published as a figure.
• Advertising is off. If that changes, this page and the privacy policy will say so first.