Mortgage rate locks explained: when to lock, how long, and what a float-down is
The short answer
A rate lock is a lender's commitment to hold a specific interest rate and points for a set period, commonly 30 to 60 days, while your loan closes. If rates rise during the lock, your rate stays the same; if they fall, you usually keep the locked rate unless you have a float-down option. Most borrowers lock once they have a signed purchase contract or have decided to refinance.
Choosing a lock period
Match the lock to your closing date plus a buffer. Longer locks, such as 60 to 90 days, often cost a little more in rate or points. Ask your loan officer how long similar files are taking to close.
If your lock expires
Delays happen. Lenders usually offer extensions for a fee, often a fraction of a point for each extra week or two. Respond quickly to document requests to avoid needing one.
Float-down options
A float-down lets you take a lower rate if market rates drop meaningfully after you lock. It may cost extra upfront and usually requires rates to fall by a set amount. It can be worth asking about when rates are volatile.
Lock or float?
Floating means waiting to lock in hopes that rates fall. It is a gamble. Rates rose about a full percentage point between March and September 2026, which shows how quickly a float can go wrong. If the payment at today's rate works for your budget, locking removes the risk. See how rates moved in 2026.
Common questions
Does a rate lock cost money?
Standard locks for typical periods are often included in your pricing. Longer locks, extensions, and float-down options may cost extra.
Can I switch lenders after locking?
Yes, but you lose that lock and must start over with the new lender, which can delay closing.