1 Reply Latest reply on Feb 26, 2017 4:09 PM by try67

# How to add gender and age variables to my BMI calculation?

I'm trying to build a calculator that works out the users BMI.

I've managed to get this far at the moment, however I would like to add the users age and gender to the calculation.

<!DOCTYPE html>

<html>

<html>

<title>BMI Calculator</title>

<script type="text/javascript">

function computeBMI()

{

//Obtain user inputs

var height=Number(document.getElementById("height").value);

var heightunits=document.getElementById("heightunits").value;

var weight=Number(document.getElementById("weight").value);

var weightunits=document.getElementById("weightunits").value;

//Convert all units to metric

if (heightunits=="inches") height/=39.3700787;

if (weightunits=="lb") weight/=2.20462;

if (heightunits=="cm") height/=100;

//Perform calculation

var BMI=weight/Math.pow(height,2);

//Display result of calculation

document.getElementById("output").innerText=Math.round(BMI*100)/100;

var output =  Math.round(BMI*100)/100

if (output<18.5)

document.getElementById("comment").innerText = "Underweight";

else   if (output>=18.5 && output<=25)

document.getElementById("comment").innerText = "Normal";

else   if (output>=25 && output<=30)

document.getElementById("comment").innerText = "Obese";

else   if (output>30)

document.getElementById("comment").innerText = "Overweight";

}

</script>

<body>

<h1>Body Mass Index Calculator</h1>

<p>Enter your height: <input type="text" id="height"/>

<select type="multiple" id="heightunits">

<option value="metres" selected="selected">metres</option>

<option value="inches">inches</option>

<option value="cm">cm</option>

</select>

</p>

<p>Enter your weight: <input type="text" id="weight"/>

<select type="multiple" id="weightunits">

<option value="kg" selected="selected">kilograms</option>

<option value="lb">pounds</option>

</select>

</p>

<input type="submit" value="computeBMI" onclick="computeBMI();">

<h2>This means you are: <span id="comment"></span> </h2>

</body>

• ###### 1. Re: How to add gender and age variables to my BMI calculation?

This forum is about JavaScript in PDF files, not web-pages...

However, it shouldn't be too difficult. Just do the same thing you did with the weight and height input.