Since hair transplant surgery is done under local anesthesia, it is not painful at all. The first two injections might be slightly uncomfortable but not unbearable. The second day after surgery, there might be some discomfort or pain that fades away gradually in a few days as the donor area heals.
In the first washing after bandage removal, there is some slight sting on the donor area as the tiny wounds are still open. However when you wash the second time, there won’t be any pain.