A rate lock guarantees that the interest rate you were quoted from your mortgage lender is good for a specific period of time. It also includes the points you must pay, an amount equal to 1 percent of the mortgage loan.
Don’t exceed 60 days
Should rate rise during that time, you will still receive the lower rate. However, if rates fall, you are locked into the original rate. Rate lock time periods vary, but are generally don’t exceed 60 days. Rates are usually locked after a seller has accepted the offer for a property.