Showing Pixel and Tile Coordinates

This example creates a map that displays a window with the latitude, longitude, and world, pixel, and tile coordinates for Chicago, IL. It also shows how these values change as the zoom level is adjusted.

Read the documentation.

TypeScript

function initMap(): void {
  const chicago = new google.maps.LatLng(41.85, -87.65);

  const map = new google.maps.Map(
    document.getElementById("map") as HTMLElement,
    {
      center: chicago,
      zoom: 3,
    }
  );

  const coordInfoWindow = new google.maps.InfoWindow();

  coordInfoWindow.setContent(createInfoWindowContent(chicago, map.getZoom()!));
  coordInfoWindow.setPosition(chicago);
  coordInfoWindow.open(map);

  map.addListener("zoom_changed", () => {
    coordInfoWindow.setContent(
      createInfoWindowContent(chicago, map.getZoom()!)
    );
    coordInfoWindow.open(map);
  });
}

const TILE_SIZE = 256;

function createInfoWindowContent(latLng: google.maps.LatLng, zoom: number) {
  const scale = 1 << zoom;

  const worldCoordinate = project(latLng);

  const pixelCoordinate = new google.maps.Point(
    Math.floor(worldCoordinate.x * scale),
    Math.floor(worldCoordinate.y * scale)
  );

  const tileCoordinate = new google.maps.Point(
    Math.floor((worldCoordinate.x * scale) / TILE_SIZE),
    Math.floor((worldCoordinate.y * scale) / TILE_SIZE)
  );

  return [
    "Chicago, IL",
    "LatLng: " + latLng,
    "Zoom level: " + zoom,
    "World Coordinate: " + worldCoordinate,
    "Pixel Coordinate: " + pixelCoordinate,
    "Tile Coordinate: " + tileCoordinate,
  ].join("<br>");
}

// The mapping between latitude, longitude and pixels is defined by the web
// mercator projection.
function project(latLng: google.maps.LatLng) {
  let siny = Math.sin((latLng.lat() * Math.PI) / 180);

  // Truncating to 0.9999 effectively limits latitude to 89.189. This is
  // about a third of a tile past the edge of the world tile.
  siny = Math.min(Math.max(siny, -0.9999), 0.9999);

  return new google.maps.Point(
    TILE_SIZE * (0.5 + latLng.lng() / 360),
    TILE_SIZE * (0.5 - Math.log((1 + siny) / (1 - siny)) / (4 * Math.PI))
  );
}

declare global {
  interface Window {
    initMap: () => void;
  }
}
window.initMap = initMap;

JavaScript

function initMap() {
  const chicago = new google.maps.LatLng(41.85, -87.65);
  const map = new google.maps.Map(document.getElementById("map"), {
    center: chicago,
    zoom: 3,
  });
  const coordInfoWindow = new google.maps.InfoWindow();

  coordInfoWindow.setContent(createInfoWindowContent(chicago, map.getZoom()));
  coordInfoWindow.setPosition(chicago);
  coordInfoWindow.open(map);
  map.addListener("zoom_changed", () => {
    coordInfoWindow.setContent(createInfoWindowContent(chicago, map.getZoom()));
    coordInfoWindow.open(map);
  });
}

const TILE_SIZE = 256;

function createInfoWindowContent(latLng, zoom) {
  const scale = 1 << zoom;
  const worldCoordinate = project(latLng);
  const pixelCoordinate = new google.maps.Point(
    Math.floor(worldCoordinate.x * scale),
    Math.floor(worldCoordinate.y * scale)
  );
  const tileCoordinate = new google.maps.Point(
    Math.floor((worldCoordinate.x * scale) / TILE_SIZE),
    Math.floor((worldCoordinate.y * scale) / TILE_SIZE)
  );
  return [
    "Chicago, IL",
    "LatLng: " + latLng,
    "Zoom level: " + zoom,
    "World Coordinate: " + worldCoordinate,
    "Pixel Coordinate: " + pixelCoordinate,
    "Tile Coordinate: " + tileCoordinate,
  ].join("<br>");
}

// The mapping between latitude, longitude and pixels is defined by the web
// mercator projection.
function project(latLng) {
  let siny = Math.sin((latLng.lat() * Math.PI) / 180);

  // Truncating to 0.9999 effectively limits latitude to 89.189. This is
  // about a third of a tile past the edge of the world tile.
  siny = Math.min(Math.max(siny, -0.9999), 0.9999);
  return new google.maps.Point(
    TILE_SIZE * (0.5 + latLng.lng() / 360),
    TILE_SIZE * (0.5 - Math.log((1 + siny) / (1 - siny)) / (4 * Math.PI))
  );
}

window.initMap = initMap;

CSS

/* 
 * Always set the map height explicitly to define the size of the div element
 * that contains the map. 
 */
#map {
  height: 100%;
}

/* 
 * Optional: Makes the sample page fill the window. 
 */
html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
}

HTML

<html>
  <head>
    <title>Showing Pixel and Tile Coordinates</title>
    <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>

    <link rel="stylesheet" type="text/css" href="./style.css" />
    <script type="module" src="./index.js"></script>
  </head>
  <body>
    <div id="map"></div>

    <!-- 
     The `defer` attribute causes the callback to execute after the full HTML
     document has been parsed. For non-blocking uses, avoiding race conditions,
     and consistent behavior across browsers, consider loading using Promises
     with https://www.npmjs.com/package/@googlemaps/js-api-loader.
    -->
    <script
      src="https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initMap&v=weekly"
      defer
    ></script>
  </body>
</html>

Try Sample

Clone Sample

Git and Node.js are required to run this sample locally. Follow these instructions to install Node.js and NPM. The following commands clone, install dependencies and start the sample application.

  git clone -b sample-map-coordinates https://github.com/googlemaps/js-samples.git
  cd js-samples
  npm i
  npm start

Other samples can be tried by switching to any branch beginning with sample-SAMPLE_NAME.

  git checkout sample-SAMPLE_NAME
  npm i
  npm start