How is my final mortgage rate calculated, and when is that rate confirmed?

Interest rates fluctuate daily. Rates available when you apply may be different than the rates available when you decide to lock your interest rate. By locking, you protect your selected rate for a stated period of time regardless of market fluctuation. Your credit rating, debt-to-income ratio and combined loan-to-value ratio will determine your final mortgage rate. Your rate can not be locked until these are determined.