diet profile plugin

I need a plugin for my site. I currently have a place where people can request a free diet profile. The diet profile asks for the age, height, gender, target weight and current weight. Then I get an email from my site with that info. I then give the person a Body Mass Index number which corresponds to the BMI chart. However, I have to look up the number based on their information. I need a plugin that will automatically calculate the person's BMI number and send it to them with some pre=written text and the body mass index chart. I also need this installed.