Well, I am 145 lbs and 5'10" and the seats on cheap flights I cannot put my elbows beside me inside the arm rest area if I sit straight unless I do some body contortion. Those seats are small as fuck. But I still have room to sit on my feet or pull my legs up. I looked it up. 17.5 inches. not even the size of a standard closet (24", width of hangers + 2 inches on each side I think)