Most hair loss is on the crown. How many grafts would I need? (Photo)

An in person consult is a good idea, but it looks like 1500g could do the job in something like this.

The most important thing is to make sure this represents genetic hair loss and not another type of hair loss. It's actually not clear from the photos if this is only genetic hair loss.  If it is, the area is approx 36-40 sq cm which means 1400-1600 grafts should do nicely.