"Ideal Weight"

What source do you use to determine the ideal weight for your age and height. Some sites I view have the same weight for a 30 year old and a 50 year old. Umm I don't think so. I'm somewhat at a plateau and I'm wondering if I've hit my ideal weight.

I use prevention.com It takes more than just your age into consideration.

When I was in my 20s, I was 5-10 lbs above what I was told my "ideal weight" was - I had an 17 inch waist, and had a very weak immune system (I wasn't healthy). When I finally gained another 5-10 lbs I got sick less often and had more energy - to me this is my ideal weight. For ME, as far as ideal weight goes, I won't be looking to see what someone else says

Since I posted that, I've added one and half pounds. I'm thinking I'm right at what must be ideal for me.