Mathmatical Formula Development

I am trying to create a formula for calculating body weight. I am currently using several different formulas to accomplish this, but would like to create a new version with the help of a mathematics expert. We can use the other formulas for reference, if needed; however, this new formula we develop will need to be unique and just as accurate. If you have any questions, please let me know. Will provide formulas and additional details when freelancer has been chosen.