There is no simple formula, it depends upon muscle bulk and bone density. However the BMI can be useful, as can the measure of your hips to your waist (http://www.mydr.com.au/tools/waist-to-hip-calculator).
eat more protein
I think "ideal weight" was something like 120lbs at 5 feet plus 5lbs per inch for men. So like 155 or so.
Your body will last longer if it is not burdened with extra weight.
fattening up for Christmas are we
naa im over 200 lbs
ur still young man u will
its true when i was ur age i was tiny