When you're promised a "rate lock" from a lender, it means that you are guaranteed to keep a specific interest rate for a certain number of days for the application process. This means your interest rate won't rise during the application process.
Rate lock periods can be various lengths of time, between fifteen to sixty days, with the longer spans generally costing more. You can get a longer period for your lock, but in doing so, will likely have a higher rate than you would have with a shorter rate lock span of time
There are more ways to get a good rate, besides choosing a shorter rate lock period. The more the down payment, the better your rate will be, as you will be starting with more equity. You can pay points to bring down your interest rate for the loan term, meaning you pay more initially. One strategy that is a good option for some is to pay points to bring the rate down over the life of the loan. You'll pay more initially, but you will save money, especially if you keep the loan for a long time.
Do you have a question regarding a mortgage program?