A mortgage rate lock is a promise to you from the lender to hold a specific combination of an interest rate and points for an agreed upon time (typically 10, 15, 30, 45 or 60 days) until you can close on your home. Locking in a rate protects you from unforeseen interest rate increases that can occur in the days or weeks leading up to closing, but conversely, if the rates fall, you may not be able to take advantage of the lower rates.

Rate locks are dependent on the type of loan program, current interest rates, points, and the length of the lock. To hold a rate for longer periods of time, you usually have to agree to pay higher points or interest rates.