To calculate whether a refinance is worth it, divide your total closing costs by the amount you’ll save each month. The result is your break-even point: the number of months before your savings overtake what you spent to refinance. If you plan to stay in your home longer than that, refinancing likely makes financial sense. But the break-even calculation is just the starting point. A full analysis also considers what happens to your total interest over the life of the loan, whether you can drop private mortgage insurance, and how resetting your loan term changes the picture.
The Break-Even Calculation
The core formula is straightforward: total closing costs divided by monthly savings equals your break-even point in months. If refinancing costs you $6,000 and your monthly payment drops by $200, you break even in 30 months. Every month you stay in the home after that, the $200 savings is money in your pocket.
Your monthly savings is the difference between your current payment (principal, interest, and any PMI) and what you’d pay on the new loan. If your current payment is $1,850 and the new one would be $1,600, your monthly savings is $250. With $5,000 in closing costs, your break-even point is 20 months.
This version of the calculation focuses purely on cash flow. It tells you when your lower payment has recouped the upfront cost. For many homeowners, especially those unsure how long they’ll stay, this is the most useful number. If you’re likely to move or refinance again within two to three years, a break-even point of 36 months means you probably won’t come out ahead.
What Closing Costs to Include
Closing costs on a refinance typically run 2% to 5% of the new loan amount. On a $300,000 loan, that’s $6,000 to $15,000. The major line items break down like this:
- Origination or underwriting fee: 0.5% to 1.5% of the loan amount. On a $300,000 loan, that’s $1,500 to $4,500.
- Appraisal fee: $300 to $1,000, depending on property size and location.
- Title services: $300 to $2,000, covering the title search, title insurance, and related fees.
- Discount points: Each point costs 1% of the new loan amount and buys a lower interest rate. One point on a $300,000 loan is $3,000.
If your lender offers a “no-closing-cost” refinance, the fees aren’t waived. They’re rolled into the loan balance or offset by a higher interest rate. Either way, you’re still paying them. Factor the true cost into your break-even math regardless of how the fees are structured.
Why Monthly Savings Can Be Misleading
A lower monthly payment feels like savings, but it can mask a much larger cost. When you refinance into a new 30-year mortgage after already paying on your current loan for several years, you’re stretching your remaining balance over a longer repayment period. That resets the clock.
Say you’re seven years into a 30-year mortgage. You have 23 years left. If you refinance into a new 30-year loan, you’ll now be paying for a total of 37 years. Even at a lower rate, the extra years of interest accumulation can cost tens of thousands of dollars more than simply keeping the original loan. One detailed analysis found that refinancing at the same interest rate, while producing lower monthly payments, increased total interest costs by more than $77,600 over the life of the loan.
This is why the monthly payment break-even calculation alone doesn’t tell the whole story. Your payment drops, but you may pay far more in interest over time.
How to Compare Total Interest Costs
To get the full picture, calculate the total interest you’ll pay under each scenario. You need two numbers: total interest remaining on your current loan, and total interest on the proposed new loan.
For your current loan, multiply your monthly payment by the number of months remaining, then subtract your current balance. If you owe $250,000 with 20 years left and your payment is $1,500, you’ll pay $360,000 total. Subtract the $250,000 balance, and you’ll pay $110,000 in interest over those 20 years.
For the new loan, do the same math with the new payment, new term, and new balance (including any rolled-in closing costs). If the new loan is $255,000 at a lower rate with a $1,350 payment over 30 years, you’ll pay $486,000 total, or $231,000 in interest. That “savings” of $150 per month actually costs you $121,000 more in interest over time.
The fix is to refinance into a shorter term, or to keep making your old, higher payment on the new loan. If you refinance at a lower rate but keep paying $1,500 instead of the new minimum of $1,350, you’ll pay off the loan faster and capture the interest savings the lower rate was supposed to deliver.
When PMI Removal Changes the Math
If you’re currently paying private mortgage insurance, refinancing can eliminate it and improve your break-even calculation significantly. PMI typically costs about 0.5% of your loan balance per year. On a $300,000 loan, that’s roughly $125 per month.
PMI is required when your loan-to-value ratio (LTV) is above 80%, meaning you have less than 20% equity. If your home has appreciated since you bought it, a refinance appraisal could show enough equity to drop below that 80% threshold. When you refinance, the “original value” resets to the new appraised value. So if your home was worth $350,000 when you bought it but is now worth $420,000, and you owe $320,000, your LTV based on the new appraisal is about 76%, well under the 80% cutoff.
Eliminating PMI adds directly to your monthly savings. If a rate reduction saves you $100 per month and dropping PMI saves another $125, your total monthly savings is $225. That dramatically shortens the break-even timeline. On its own, you can ask your current servicer to cancel PMI once your balance reaches 80% of the original purchase value, and it automatically drops at 78%. But if your home’s value has risen substantially, refinancing may be the faster path to eliminating it.
A Step-by-Step Worksheet
Run through these steps to make your decision:
- Step 1: Get a loan estimate from at least two lenders. Note the interest rate, monthly payment, and itemized closing costs.
- Step 2: Calculate monthly savings by subtracting the new payment (including PMI if applicable) from your current payment.
- Step 3: Divide total closing costs by monthly savings to find your break-even point in months.
- Step 4: Compare that break-even point to how long you plan to stay in the home. If you’ll stay longer, the refinance passes the first test.
- Step 5: Calculate total interest on both your current loan and the new loan to see whether you’ll pay more or less over the full repayment period.
- Step 6: If the new loan has a longer term, calculate what happens if you make extra payments equal to the difference between your old and new payment. This shows you the true savings from the lower rate without the cost of extending the term.
Rate Drops That Typically Justify Refinancing
The old rule of thumb was that refinancing made sense if you could cut your rate by at least one percentage point. That’s a reasonable starting point, but the real answer depends on your loan balance and closing costs. On a $400,000 loan, even a half-point rate reduction saves roughly $120 per month, which can recoup $6,000 in closing costs in about 50 months. On a $150,000 loan, that same half-point drop saves closer to $45 per month, pushing the break-even point past 10 years.
Larger loan balances amplify the impact of small rate changes. If you have a big balance and plan to stay for several more years, a rate drop that seems modest can still be worth pursuing. Run the numbers with your actual figures rather than relying on any single rule of thumb.