You don’t need to install Google Earth to open a KML or KMZ file. Google Earth on the web opens them in your browser, Google My Maps imports them into a map of your own, and Mapsfera’s KML viewer shows them on a map without uploading them anywhere, with a count of what’s inside, measurements and conversion to other formats. Here are the three ways, what’s inside a KMZ and what to do when a file won’t open.
KML and KMZ: what they are
KML is Google Earth’s format, now an Open Geospatial Consortium (OGC) standard. It’s a text file that stores placemarks (points), lines, polygons, folders and styles, with coordinates in longitude and latitude.
KMZ is a zipped KML. According to Google’s documentation, it holds a single KML file, named doc.kml by default, plus folders with the icons, images and models it uses:
So if a program won’t take a KMZ, rename .kmz to .zip, unzip it and open the doc.kml inside. That’s what Google’s own documentation says to do to get at the contents.
In your browser, with Google Earth
Google Earth on the web opens a KML or KMZ from your computer with nothing to install and, according to its help, without signing in:
- Open Google Earth in your browser.
- At the bottom left of the home screen, click Open local KML editor.
- Click Open KML from device and select your file.
Changes aren’t saved on their own: save or download them. According to Google, autosave only works in Chromium-based desktop browsers. To add the file to a Google Earth project, stored in your Google Drive, open the project and go to File > Import file to your project.
On a phone, the Google Earth app does the same from its Local tab: New > Local KML editor, then Open KML/Z from device.
In Google My Maps
If you want the KML in a map of your own that you can share, import it into Google My Maps. You need a Google account:
- Open a map or create a new one.
- In the map legend, click Add layer.
- Under the new layer, click Import.
- Upload the file and click Select.
It has two limits: KML and KMZ files up to 5 MB unzipped, and some features don’t come through: balloons with HTML or JavaScript, tours, time-based features, overlays, 3D models and folders.
On Mapsfera, no account and no upload
- Open the KML viewer.
- Drop the KML or KMZ file onto the tool or choose it with the button.
- See it on the map with its own colors and folders. Tap a feature on the map or in the list to see its name, description and data.
The file is read in your browser and never uploaded, so you can open one with private data, like a farm’s fields or a sales route. The viewer counts the points, lines and polygons and measures lengths and areas on the ellipsoid.
With the example from the button, a walk through Madrid’s museum district, you get:
| What’s inside | Result |
|---|---|
| Features | 5: 3 points, 1 line and 1 polygon, in 3 folders |
| The line (Paseo del Prado) | 0.29 mi |
| The polygon (Retiro Park) | 292 acres, with a 2.76 mi perimeter |
When a file won’t open
- It’s too big for My Maps. Open it in Google Earth or on Mapsfera, or convert it and split it.
- The icons don’t show. If the KML points to icons on the internet, Mapsfera’s viewer draws them as circles and tells you which sites they come from, with a button to load them: opening a file shouldn’t contact other servers without you knowing.
- It’s a KMZ and the program won’t take it. Rename it to
.zip, unzip it and open thedoc.kml. - It’s actually a GPX or a GeoJSON. Use the GPX viewer or the GeoJSON viewer.
Convert it to another format
From Mapsfera’s viewer you can download it as KMZ, GeoJSON, GPX or CSV:
- GPX, for a GPS unit, a watch or a hiking app. If it’s a trail, see its climbs with the GPX elevation profile.
- GeoJSON, for websites and programs like QGIS.
- CSV, with the geometry as WKT, the column QGIS and Google My Maps read. If you have a spreadsheet and want to go the other way, see how to map addresses from a spreadsheet.