Originally Posted by
VegasGambler
They are the same size -- both of them are the width of your seat. Ignore the posts supporting the seats in front of you; they do not form borders for your space.
You can ignore the "posts" if you like but you can't ignore the inhibiting frame around the isle seat at floor level to prevent undedseat stored bags from sliding into the isle. Therefore, the space, is not, the width of the isle seat. The space from the post to the frame is, in fact, smaller than the space from the other post to the fuselage.
James