Bone density and muscle mass are also important considerations when deciding your optimal weight. Someone who naturally has more bone density will often have thicker frame. As well as DNA playing a big part, Bone density can be accumulated through an active life style one of which involves years of repetitive weight resistance. Obviously some peoples bodies react differently to such activities with metabolism being one of the main factors and general state of health which can effect they rate at which your body will build muscle mass, store water, expend energy and so forth.
I am not sure about Body/weight calculators on the internet...but if all they do is count your Height for a BMI indicator, then I would call it a gimick. You could in fact end up looking ill trying to reach its recommended targets, not to mention quite depressed as you wonder why you can never quite stay at that target.
Go check out a recommended doctor for advise...although, some of them just go willy nilly with the BMI as well...
It's just IMO, but I know there are many others out there that agree with me on this.
How tall are you?
How OLD are you?
What censored are you?
What body shape are you? There are 3 main body types...Endomorph, Ectomorph, or Mesomorph...they are all relevant to my first paragraph!
What has your Sporting/Activity & Work history been over the years?.........or physical activity!
What medical conditions do you have or of had?
Do you gain weight easily?
Do you gain muscle easily?
What have your eating habits been?
Do you drink alcohol/take drugs or an medication? Any of these can adversely effect you weight and you history with either one also effects your body chemistry.
Sorry, I do get carried away at times...what I am getting at is that you should not rely on some weight calculator...the main factors to consider would be...Height/age/censored/and Body type...if you can find something that considers these factors then you will get closer to the mark for your body. The other things I mention also will affect your progress and may also help you to make more informed decisions embarking on a new and healthier lifestyle.
I wish you the best of luck with it...