If you weigh 120 pounds and you are 5 foot 5 inches are you over weight?

not at all actually look at what kind of frame she or he is built like small medium large then go here

http://www.healthchecksystems.com/heightweightchart.htm

even though you are a teenager and still technically growing, you are judged on the adult weight and height chart.

120 pounds is roughly 8.6 stone

with your height you are in the 'average' zone

with your height if you get over 9 and a half stone (135 pounds i think) then you have just entered the 'overweight' zone, but that's still ok

as long as you don't end up in the 'fat' and to get into that you need to weigh 12 stone (168 pounds)

so roughly, no your not overweight.