Mortgage Refinance Break-Even Calculator

Refinancing replaces your current mortgage with a new one — usually to lower your interest rate and reduce your monthly payment. The catch is that you pay closing costs up front (typically 2% to 5% of the loan amount), and you only come out ahead if you stay in the home long enough to recoup them.

This calculator computes both your current monthly principal-and-interest payment and the new one based on the rates and terms you enter. Then it shows when the savings catch up to the closing costs.

The Break-Even Formula

Break-even (months) = Closing Costs ÷ Monthly Payment Savings

If you plan to stay in the home longer than the break-even period, refinancing makes financial sense. If you’ll move sooner, the closing costs eat the savings.

How the Monthly Payment Is Calculated

Both the current and new payments use the standard amortization formula:

M = P × [r(1+r)^n] ÷ [(1+r)^n − 1]

Where:

• M = monthly principal + interest payment
• P = principal (loan balance)
• r = monthly rate (annual rate ÷ 12)
• n = number of payments (years × 12)

The Term-Reset Trap

This is the part most “refinance to save money” pitches gloss over. If you have 20 years left on a 30-year mortgage and refinance into a fresh 30-year loan, your monthly payment drops — but you’re now paying interest for 30 more years instead of 20. Even at a lower rate, your total interest paid over the life of the loan can be higher.

The calculator shows you:

• Total interest if you stay with your current loan
• Total interest if you refinance (assuming you keep the new loan to maturity)

If the refinance number is higher than the stay-put number, the lower monthly payment is misleading — you’re stretching the debt out.

Worked Example

You have $260,000 left on a 30-year mortgage at 7.5%, with 22 years (264 months) remaining. A lender offers 6.0% on a fresh 25-year refinance. Closing costs: $5,500.

• Current monthly P&I: $2,000 (calculated from $260,000 at 7.5% / 22 years)
• New monthly P&I: $1,675 (calculated from $260,000 at 6.0% / 25 years)
• Monthly savings: $325
• Break-even: $5,500 ÷ $325 ≈ 17 months

If you stay in the home another 5 years past the break-even, you save roughly $325 × 60 = $19,500 beyond the closing costs.

But check total interest:

• Stay with current loan: $264 × $2,000 − $260,000 ≈ $268,000 in remaining interest
• Refinance for 25 years: $300 × $1,675 − $260,000 ≈ $242,500 in interest

In this case, even with the longer term, the lower rate wins on total interest by about $25,500. Always check both numbers.

What Counts as Closing Costs?

Typical refinance closing costs include origination fees, appraisal, title search, title insurance, attorney fees, recording fees, prepaid interest, and escrow setup. Most lenders quote 2% to 5% of the loan amount. Some “no-cost” refis fold the costs into a slightly higher rate — same money, just hidden.

When to Skip a Refinance

• The break-even period is longer than you plan to stay in the home
• The new total interest is higher than your current path
• Your credit has dropped since the original loan (you may not qualify for the rate quoted)
• You’re already deep into your current mortgage (most of the early-year interest is already paid)

This calculator is a starting point, not financial advice. Loan terms vary; consult a mortgage professional before committing.