function calculate(){
	var output = 0;
	var bmi = 0;
	var comment = 0;
	var h = Number(document.forms[0].h.value);
	var w = Number(document.forms[0].w.value);
	var h_unit = Number(document.forms[0].h_unit.selectedIndex);
	var w_unit = Number(document.forms[0].w_unit.selectedIndex);
	if ( h_unit == 0 ){ h = h * 0.0254;}
	if ( h_unit == 1 ){ h = h * 0.01;}
	if ( w_unit == 0 ){ w = w * 0.45359237;}
	if ( w_unit == 1 ){ w = w * 1;}
	bmi = w / (h * h );
	if ( bmi < 18 ){ comment = "Under Weight";}
	if ( ( bmi >= 18 ) && ( bmi < 25 ) ){ comment = "Normal Weight";}
	if ( ( bmi >= 25 ) && ( bmi < 27 ) ){ comment = "Overweight";}
	if ( ( bmi >= 27 ) && ( bmi < 30 ) ){ comment = "Obese";}
	if ( ( bmi >= 30 ) && ( bmi < 35 ) ){ comment = "Very Obese";}
	if ( ( bmi >= 35 ) && ( bmi < 40 ) ){ comment = "Very Obese";}
	if ( bmi >= 40 ) { comment = "Extremely Obese";}
	document.forms[0].bmi.value = Math.round( 10 * bmi)/ 10;
	document.forms[0].comment.value = comment;
}