Knowing that you are 30 years old and assuming that your hair is of a medium thickness (not fine or coarse), it would take about 1800 grafts to fill in this area. More if it were fine, less if it was coarse. The crown is where the hair changes direction, so a good swirl needs to be created which takes more grafts. Thank you for putting your fingers in the photo so it give me a good way to estimate the size of the balding area