function calculate(){
	var unitType = document.getElementById('units').value;
	var totalArea = new Number(document.getElementById('total_floor_area').value);
	if(totalArea == '') totalArea = 20;
	var flooringRequired = new Number(totalArea*1.1);
	flooringRequired = flooringRequired.toFixed(2);
	if(unitType == 1) 
	{
		flooringRequired = new Number(flooringRequired*0.09290304);
		var packsRequired = new Number(flooringRequired/unitSize);
		packsRequired = Math.ceil(packsRequired);
		var unitSizeInFeet = new Number(unitSize/0.09290304);
		flooringRequired = new Number(packsRequired*unitSizeInFeet);
		var unitText = "sqf";
	}else{
		var packsRequired = new Number(flooringRequired/unitSize);
		packsRequired = Math.ceil(packsRequired);
		flooringRequired = new Number(packsRequired*unitSize);
		var unitText = "sqm";
	}
	var price = new Number(packsRequired*packPrice*VAT);
	document.getElementById('total_area').innerHTML = totalArea+' '+unitText;
	document.getElementById('flooring_required_text').innerHTML = flooringRequired.toFixed(2)+' '+unitText;
	document.getElementById('unit_selected').innerHTML = unitText;
	document.getElementById('flooring_required').innerHTML = flooringRequired.toFixed(2)+' '+unitText;
	document.getElementById('packs_required').innerHTML = packsRequired;
	document.getElementById('price').innerHTML = price.toFixed(2);
}