It's difficult to find accurate measurements on the hand size of Julius Erving. Fortunately, Dr J did us a favour by comparing his hands with Noah Vonleh, whose hand size we know with certainty. Vonleh’s hand length appeared to be about a quarter of an inch longer than Erving's. However, there was very little difference in their span. By the way, Vonleh's hand size is 9.75 inches in length and 11.75 inches in span and is one of the largest ever measured at the Combine. Dr J’s hand length is probably somewhere around 9.5 inches. His hand span is also probably around 11.75 inches. You can find the pic of them comparing hands in the link below.