BOS-SFO (direct)
2,704 miles posted for years by MP
2,700 miles per your tool


BOS-:LAX (direct)
2,611 miles posted for years by MP
2,608 miles per your tool


BKK-NRT
2,887 miles posted for years by MP
2,889 miles per your tool


I am sure every other city pair is off.

Not sure where you are getting your data?

Through flights are way off, ~ 100 miles or so.

I think the PDF timetable is a lot more accurate?