how much will my credit score decrease for each inquiry

A single hard inquiry, which occurs when you formally apply for a loan or a new credit card, will typically cause a temporary decrease in your credit score by a few points, generally ranging from 3 to 10 points. The exact impact depends on your existing credit profile. It is important to remember that soft inquiries, such as checking your own credit score or a pre-approval check by a lender, do not affect your score at all. Multiple hard inquiries over a short timeframe can cumulatively have a more negative effect.