dopecalc

Refinance Calculator

Evaluate whether refinancing your mortgage makes financial sense by comparing monthly savings, break-even point, and lifetime interest savings.

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About this Calculator

Evaluate whether refinancing your mortgage makes financial sense by comparing monthly savings, break-even point, and lifetime interest savings.

Formula & Calculations

Formula

Monthly Payment = P × [i(1+i)^n] / [(1+i)^n - 1]; Savings = Old Payment - New Payment; Break-Even = Closing Costs / Monthly Savings
Where:
  • B=Current loan balance
  • CC=Closing costs for the new loan
  • r_current=Current annual interest rate
  • r_new=New annual interest rate
  • T_current=Remaining term of current loan in years
  • T_new=New loan term in years

Assumptions

  • Assumes closing costs are rolled into the new loan balance (financed).
  • Calculates monthly payment using standard amortization formula.
  • Does not account for tax implications or escrow changes.
  • Break-even analysis assumes you stay in the home through the break-even point.

Calculation Examples

Example 1

Inputs:Balance: $250,000, Current Rate: 7.5%, Remaining: 25yr, New Rate: 6.0%, New Term: 30yr, Closing: $5,000
Result:Monthly Savings: $248, Break-Even: 21 months, Lifetime Savings: $74,834

Refinancing from 7.5% to 6.0% saves $248/month. It takes 21 months to recoup the $5,000 closing costs. Over the full term, you save nearly $75,000.

Example 2

Inputs:Balance: $180,000, Current Rate: 6.5%, Remaining: 20yr, New Rate: 5.5%, New Term: 15yr, Closing: $3,500
Result:Monthly Payment: $1,354 (old) vs $1,470 (new), Lifetime Savings: $57,128

Switching to a 15-year term at a lower rate increases the monthly payment slightly but saves over $57,000 in total compared to the remaining 20 years at 6.5%.

Example 3

Inputs:Balance: $120,000, Current Rate: 4.5%, Remaining: 10yr, New Rate: 4.25%, New Term: 10yr, Closing: $4,000
Result:Monthly Savings: $16, Break-Even: 20+ years, Lifetime Savings: $1,920

A small rate reduction with high closing costs may not justify refinancing if you plan to move before the break-even point.

Frequently Asked Questions

When does it make sense to refinance?

Refinancing typically makes sense when you can lower your interest rate by at least 1%, plan to stay in the home past the break-even point, or want to switch from an adjustable-rate to a fixed-rate mortgage. You can also refinance to shorten your term or tap equity.

What closing costs should I expect when refinancing?

Refinance closing costs typically run 2-5% of the loan amount and may include origination fees, appraisal, title search, credit report, and recording fees. Some lenders offer no-closing-cost refinances at a slightly higher interest rate.