I JUST watched the official video from IP on this, this morning!
Dr. W. (I'm not being overly chummy; I just honestly can't remember his whole last name
) says that the goal is to stay under 40 net grams of carbohydrates, in general. But individuals vary, so some people can have fewer than that, while others can have more.
"Net grams" refers to total grams of carbohydrate, minus grams of fiber.