Mortgage Lock-In & Move-or-Stay Calculator: What Moving Really Costs a Low-Rate Owner
Millions of owners are sitting on mortgages far below today's rates. This calculator shows what that loan is worth, what a move would do to your monthly payment, what selling and buying cost, and the rate that would make the move payment-neutral.
Enter your current loan and the move you're weighing. Everything stays in your browser. The rate field starts at 7.03%, Freddie Mac's 30-year average on September 24, 2026; use a lender's quote if you have one.
Your home and mortgage now
The move
| Line | Amount |
|---|
Principal and interest only. Property taxes, insurance, HOA dues and mortgage insurance come on top, and they change with the home and the price.
How the Calculator Works
Lock-in value. Your mortgage is worth the difference between what you owe and the present value of your remaining payments at today's rate. With the defaults, a $250,000 balance at 3% with 25 years left costs $1,186 a month; at 7.03% those payments are worth $167,283, so the loan is worth about $82,717 to its owner. It's the same logic behind our guide to what a low-rate mortgage is worth.
The move. The sale price minus the balance, selling costs and moving costs, plus any extra cash, pays the buying costs first; what's left is the down payment. The new loan is the price minus that down payment. In the example, selling a $450,000 home costs $27,000 at 6%, buying a $500,000 home costs $15,000 at 3%, and $5,000 goes to the movers, leaving a $153,000 down payment and a $347,000 loan. At 7.03% for 30 years that's $2,316 a month, $1,130 more than today.
Cost over the years you'd stay. One-time costs of $47,000 plus seven years of the higher payment come to about $141,926. And rates would have to fall to about 1.43% for the new payment to match the old one.
Reading the Result
- A big lock-in value means your current loan is cheap money. Giving it up is a real cost, even though it never appears on a closing statement.
- The monthly change mixes two things: today's higher rate, and a bigger or smaller loan. The table's second line isolates the rate: the same balance refinanced at today's rate.
- The cost over the years you'd stay is a cash-flow total. Set it against what the move is worth to you: space, schools, a shorter commute, being near family.
- The break-even rate tells you whether waiting for rates to fall is realistic. If it's far below any rate seen in years, waiting won't close the gap.
What the Calculator Leaves Out
It counts principal and interest only, not property taxes, insurance, HOA dues or mortgage insurance. It ignores home-price growth, the faster principal paydown on an older loan, and tax effects; most owners can exclude up to $250,000 of gain on a home sale ($500,000 for married couples). It doesn't model the alternatives: assuming a seller's low-rate loan, buying the rate down, renovating instead, or renting out the current home. U.S. mortgages generally aren't portable; see what's real about portable and 50-year loans. For current rates and prices, see our mortgage and housing statistics.