Last updated: October 5, 2026 · Rates in the example are illustrations, not current market rates.
Mortgage rates can change every day. A rate lock protects you from increases between the time you apply and the time you close. Choosing when to lock and for how long can be worth thousands of dollars.
What a rate lock does
A rate lock is the lender’s commitment to give you a specific interest rate and points for a set number of days, commonly 30, 45 or 60. If rates rise during that period, your rate stays the same. If they fall, you generally keep the locked rate unless you have a float-down option.
The lock depends on your application staying the same. Changes in loan amount, credit score, income, property value or loan type can change your pricing even while locked.
What a small rate move is worth
On a $300,000, 30-year loan, the difference between 6.50% and 6.75% is $49.59 a month, or about $17,852 over the full term. That is the kind of move a lock protects you from during a typical 30- to 60-day closing.
How long should your lock be?
- 30 days is common for refinances and quick purchases.
- 45 to 60 days gives more room for appraisals, inspections and underwriting.
- Longer locks for new construction may cost more, through a higher rate or an upfront fee.
Pick a lock period that covers your expected closing date with some margin. Extending an expiring lock can cost money, and if it expires, you may have to accept current rates.
When to lock
- For a purchase: usually after you have a signed contract and have chosen your lender.
- For a refinance: once you have compared Loan Estimates and chosen a lender. See how to refinance your mortgage.
- Nobody can reliably predict rate moves. If today’s payment works for your budget, locking removes the risk.
Get the lock in writing
Ask for written confirmation showing the rate, points, lock expiration date and any fees, so there is no confusion later. Your Loan Estimate also shows whether the rate is locked and until when. The CFPB suggests asking each lender about its rate lock policies, including how long the lock lasts and what happens if closing is delayed.
Float-down options
Some lenders offer a float-down: if rates fall by a set amount during your lock, you can take the lower rate once. Ask about the cost and conditions; it is most useful when rates are volatile.
Avoid delays that break your lock
- Send documents quickly and respond to underwriting requests.
- Schedule the appraisal and inspection early.
- Don’t take on new debt or change jobs; see protecting your pre-approval.
Compare offers by rate and fees in APR vs. interest rate, and estimate payments in our mortgage calculator.
Frequently asked questions
What is a mortgage rate lock?
A rate lock is a lender’s commitment to hold a specific interest rate and points for a set period, such as 30, 45 or 60 days, while your loan is processed, as long as nothing in your application changes.
Does it cost money to lock a mortgage rate?
Standard locks are often included in your pricing, but longer locks can come with a higher rate or a fee. Extending an expiring lock may also cost money.
When should I lock my rate?
Most borrowers lock once they have a signed purchase contract or have chosen a lender for a refinance, and when the lock period comfortably covers the expected closing date.
What is a float-down option?
A float-down lets you get a lower rate if market rates fall during your lock period. Not every lender offers it, and it may have a cost or conditions.
Sources: CFPB: What is a rate lock?; CFPB: Buying a House. Example calculations by ToolStackIA.
This article is for educational purposes only and is not financial advice. Loan programs, rates and rules change; confirm details with your lender or a HUD-approved housing counselor.