$(document).ready(function() {
//These are the amount of mm in each drop down menu type
var array = new Array();
array['centimeters'] = '10';
array['inches'] = '25.4';
//Find the width in mm
var widthVal = $('#width').val();
var widthType = $('#measure-type').val();
var width = widthVal * array[widthType];
//Find the length in mm
var lengthVal = $('#length').val();
var lengthType = $('##measure-type').val();
var length = lengthVal * array[lengthType];
//Find the depth in mm
var depthVal = $('#depth').val();
var depthType = $('#measure-type').val();
var depth = depthVal * array[depthType];
//Find the total volume
var volume = length * depth * width;
document.getElementById("vwater").innerHTML = volume;
});