A KML file stores location data in a format that mapping programs can read

A KML file is a text document that holds geographic information — points on a map, routes, shapes, and the details attached to them. KML stands for Keyhole Markup Language. When you save a location, a route, or a marked area from Google Maps, Google Earth, or similar programs, you are working with KML files behind the scenes.

The file itself is plain text, which means you can open it in any text editor and read the actual code. But you do not need to. Mapping software reads KML files automatically and displays them as pins, lines, and colored regions on a map. A single KML file can hold one location or hundreds of them, along with names, descriptions, images, and styling information like colors and line thickness.

KML files are useful because they are a standard format — many different programs recognize them. If you create a map in one process and want to use it in another, exporting to KML and importing into the new program usually works without conversion or data loss.

Key Takeaways

  • KML files store map data including locations, routes, shapes, and descriptions in a format that mapping programs can read and display.
  • Google Maps, Google Earth, and most other mapping applications can open, create, and export KML files.
  • You can share a KML file with someone else, and they can open it in their own mapping software to see the exact locations and routes you marked.
  • KML files are text-based, so they are small in file size and work across different operating systems and devices.

How KML files work with mapping software

When you open a KML file in Google Maps or Google Earth, the program reads the text code and converts it into visual elements on the map. A location becomes a pin. A series of connected points becomes a route or path. A closed shape becomes a filled polygon. Colors, labels, and descriptions all come from information stored in the KML code.

You create KML files by using the export or save function in mapping software. In Google Maps, you can right-click a location and select "Save place" to a list, then export that list as a KML file. In Google Earth, you can draw shapes and placemarks directly, then save the project as a KML file. Other mapping tools like ArcGIS, QGIS, and Garmin BaseCamp also support KML export and import.

The reverse process works too: if someone sends you a KML file, you can open it directly in most mapping applications. The locations and routes they marked will appear on your map when ready, without any manual entry or conversion step.

Common uses for KML files

Businesses and organizations use KML files to share location data. A real estate agent might create a KML file showing all available properties in a neighborhood and send it to a client, who can then open it in Google Maps on their phone or computer. A hiking group might create a KML file of a trail route and share it so members can follow the exact path.

Researchers and planners use KML files to document geographic information. An environmental scientist might mark contaminated sites on a map and export the data as KML for a report. A city planner might create a KML file showing proposed development zones and share it with the public for feedback.

You can also use KML files for personal projects. If you are planning a road trip, you can mark all the stops you want to make, save them as a KML file, and then open that file on your phone's mapping app while you drive. If you want to keep a record of places you have visited, you can create a KML file and add to it over time.

How to open and create KML files

Opening a KML file is straightforward. If you have Google Maps or Google Earth installed, you can usually double-click a KML file and it will open automatically. You can also drag and drop a KML file into Google Maps in a web browser, and the locations will appear on your map.

To create a KML file, start in a mapping process. Mark the locations or draw the shapes you want to save. Then use the export, save, or read option — the exact name varies by program. Google Maps calls it "Export to KML". Google Earth calls it "Save". Other programs may use "Export" or "read as KML". The file will be saved to your computer with a .kml extension.

If you need to edit a KML file, you can open it in a text editor like Notepad or Word and modify the code directly. However, this requires understanding the KML format. For most users, it is easier to open the file in mapping software, make changes visually, and export again.

KML versus other map file formats

KML is not the only format for storing map data, but it is the most widely supported. GPX files are another common format, often used for GPS devices and fitness tracking apps. GPX files focus on routes and waypoints and are simpler than KML. GeoJSON is a newer format used by web developers and mapping APIs. Shapefile is an older format used in professional GIS software.

For most everyday uses — sharing locations with friends, saving maps for personal reference, or moving data between consumer mapping apps — KML is the best choice because nearly every mapping program recognizes it. If you are working with specialized software or need a format optimized for a specific purpose, you may need to convert to GPX, GeoJSON, or another format.

Many mapping applications can convert between formats. If you have a GPX file and need KML, you can often open the GPX file in Google Earth, then export it as KML. Online conversion tools also exist, though you should be cautious about uploading sensitive location data to unfamiliar websites.

Sharing KML files safely

KML files are just text, so they can be emailed, uploaded to cloud storage, or shared through messaging apps like any other file. The recipient needs only a mapping process to open them. However, because KML files contain location data, think about what information you are sharing and with whom.

If you are sharing a KML file that marks your home, your workplace, or other sensitive locations, only send it to people you trust. If you are sharing a public map — like a list of restaurants or tourist attractions — there is no privacy concern. If you are unsure whether a KML file contains sensitive information, open it in a text editor and scan the contents before sharing.

You can also password-protect a KML file by storing it in an encrypted folder or using file encryption software. This adds a layer of security if the file is intercepted during transmission.

Frequently Asked Questions

Can I open a KML file on my phone?

Yes. On Android, you can email yourself the KML file, read it, and open it with Google Maps or another mapping app. On iPhone, you can use Google Maps, Apple Maps, or third-party apps that support KML. Some phones may require you to save the file to cloud storage first, then open it from there.

What happens if I delete a KML file?

The file is gone from your device, but the locations you marked are not deleted from the mapping app itself. If you marked locations in Google Maps, they remain saved in your Google account. The KML file is just a copy or export of that data. You can always create a new KML file from your saved locations.

Can I edit a KML file after I create it?

Yes. Open the KML file in your mapping process, make changes to the locations or shapes, and export it again. You can also edit the raw text in a text editor if you understand KML syntax, though this is not necessary for most users.

Is KML the same as a Google Map?

No. A Google Map is a map you create and store in your Google account. A KML file is a downloadable copy of that map data. You can export a Google Map as a KML file, but the KML file itself is not stored in Google — it lives on your computer or device.

Do I need special software to create a KML file?

No. Any mapping process that lets you mark locations — Google Maps, Google Earth, or others — can export to KML. You do not need to buy or install specialized software.