There is no specific blade length that is good for a carving knife. It all depends on what you want to use the carving knife for. The best length of a blade is the one that can take care of the largest meats you intend to cook with ease. For instance, if you intend to make extra-large briskets, then a 14-inch blade would be the best length. If you intend to cut a 4-pound turkey, then a 10-inch blade would do.