How many air miles from Seattle to Rome Italy?

A random search for flights from Seattle/Tacoma (SEA) to Athens (ATH) shows:

OPTION 1: 15hr 00min via Frankfurt (FRA)
SEA - FRA Lufthansa Flt 0491 Dep 02:00pm 15Jan,Fri
FRA - ATH Lufthansa Flt 5910 Dep 11:15am 16Jan,Sat
Flight Duration: 12hr 50min; Layover Time: 2hr 10min; Total Trip Time: 15hr 00min