# Show drawn polygon area

Use mapbox-gl-draw to draw a polygon and Turf.js to calculate its area in square meters.

``<!DOCTYPE html><html><head><meta charset="utf-8" /><title>Show drawn polygon area</title><meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no" /><script src="https://api.mapbox.com/mapbox-gl-js/v1.10.1/mapbox-gl.js"></script><link href="https://api.mapbox.com/mapbox-gl-js/v1.10.1/mapbox-gl.css" rel="stylesheet" /><style>	body { margin: 0; padding: 0; }	#map { position: absolute; top: 0; bottom: 0; width: 100%; }</style></head><body><style>.calculation-box {height: 75px;width: 150px;position: absolute;bottom: 40px;left: 10px;background-color: rgba(255, 255, 255, 0.9);padding: 15px;text-align: center;} p {font-family: 'Open Sans';margin: 0;font-size: 13px;}</style> <script src="https://api.tiles.mapbox.com/mapbox.js/plugins/turf/v3.0.11/turf.min.js"></script><script src="https://api.mapbox.com/mapbox-gl-js/plugins/mapbox-gl-draw/v1.0.9/mapbox-gl-draw.js"></script><linkrel="stylesheet"href="https://api.mapbox.com/mapbox-gl-js/plugins/mapbox-gl-draw/v1.0.9/mapbox-gl-draw.css"type="text/css"/><div id="map"></div><div class="calculation-box"><p>Draw a polygon using the draw tools.</p><div id="calculated-area"></div></div> <script>	// TO MAKE THE MAP APPEAR YOU MUST	// ADD YOUR ACCESS TOKEN FROM	// https://account.mapbox.com	mapboxgl.accessToken = '<your access token here>';var map = new mapboxgl.Map({container: 'map', // container idstyle: 'mapbox://styles/mapbox/satellite-v9', //hosted style idcenter: [-91.874, 42.76], // starting positionzoom: 12 // starting zoom}); var draw = new MapboxDraw({displayControlsDefault: false,controls: {polygon: true,trash: true}});map.addControl(draw); map.on('draw.create', updateArea);map.on('draw.delete', updateArea);map.on('draw.update', updateArea); function updateArea(e) {var data = draw.getAll();var answer = document.getElementById('calculated-area');if (data.features.length > 0) {var area = turf.area(data);// restrict to area to 2 decimal pointsvar rounded_area = Math.round(area * 100) / 100;answer.innerHTML ='<p><strong>' +rounded_area +'</strong></p><p>square meters</p>';} else {answer.innerHTML = '';if (e.type !== 'draw.delete')alert('Use the draw tools to draw a polygon!');}}</script> </body></html>``