I gain 2 1/4 inches simply by flexing my arm, so thats the main measurement I go by. Not sure why anyone would measure it extended as the main measurement. Pumped will add another 3/4 inch.
Yeah I gain over 2 inches when I flex (whatever bis I have peak thanks to genetics) and more if I'm pumped. So I normally say I have 14" arms, but it's over 16" if I flex. Makes me feel better