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 are 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 are 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: $2,013.73 (from $260,000 at 7.5% over 264 months)
• New monthly P&I: $1,675.18 (from $260,000 at 6.0% over 300 months)
• Monthly savings: $338.54
• Break-even: $5,500 ÷ $338.54 = 16.2 months, so 17 payments

Stay another five years past that point and the savings run to roughly $338.54 × 60 = $20,312 beyond the closing costs.

Now check total interest, which is the number the monthly saving hides:

• Stay with the current loan: 264 × $2,013.73 − $260,000 = $271,624
• Refinance for 25 years: 300 × $1,675.18 − $260,000 = $242,555

Even with three extra years of payments, the lower rate wins on total interest by $29,069. Subtract the $5,500 of closing costs and you are $23,569 ahead over the full term. Every one of these figures comes out of the calculator above.

Change one thing and the answer flips. Take the same refinance at 7.0% instead of 6.0% and the interest saving shrinks below the closing costs, at which point a lower monthly payment is costing you money in total. The calculator names that case rather than reporting the shortfall as a saving.

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 less visible.

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.