<!doctype html>
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<script src="http://code.jquery.com/jquery-1.10.1.min.js"></script>
<script type="text/javascript" src="https://www.google.com/jsapi"></script>
<script type="text/javascript">
google.load("visualization", "1", {packages:["corechart"]});
jQuery(document).ready(function() {
var dataTable = new google.visualization.DataTable();
dataTable.addColumn('string', 'Year');
dataTable.addColumn('number', 'Sales');
dataTable.addColumn({type: 'string', role: 'tooltip', 'p': {'html': true} });
dataTable.addColumn('number', 'Benefit');
dataTable.addColumn({type: 'string', role: 'tooltip', 'p': {'html': true} });
dataTable.addRows([
['2010', 1990, '<b>$1990K in our first year!</b>', 1800, '<b>$1800K in our first year!</b>'], /* support any valid html */
['2011', 1500, '<i>$1500K in our second year!</i>', 1300, '<i>$1300K in our second year!</i>'],
['2012', 1200, '$1200K in 2012.', 1040, '$1040K in 2012.'],
['2013', 1000, '$1M in sales last year.', 910, '$910K in sales last year.']
]);
var options = {
tooltip: {isHtml: true},
chartArea: {width: "90%", left: 0, top: 0}
};
// Create and draw the visualization.
var ac = new google.visualization.ColumnChart(document.getElementById('visualization'));
ac.draw(dataTable, options);
});
</script>
</head>
<body>
<div id='visualization'></div>
</body>
</html>
https://developers.google.com/chart/interactive/docs/customizing_tooltip_content
