As Sameer has said, under what situation. Other conditions are down payment, term, purchase, refinance, loan to value...?
A 628 score will have a broader range of answers once the other questions are answered. You may not qualify for some lenders at all and others will be higher than the rates you hear advertised.
The only time you really know what your rate will be is when you've applied for a specific program with a lender and have been approved. Even then, until you lock your rate for a specific time, 30 days, 45 days etc, your rate will be subject to change.
Best bet would be to meet with a local lender and discuss your situation. They will be in the best position to advise you.