What is a KML file?

What KML is

KML is a plain-text format you can open in any editor. It is used for mapping.

The extension is .kml, and the full name is Keyhole Markup Language. Both matter less than what the file can hold, which is what the rest of this page is about.

Where KML came from

Open Geospatial Consortium published it in 2008. The specification is OGC KML 2.3.

Age is worth knowing here for one practical reason: the older a format is, the more programs have had time to learn it.

The specification is public

Anyone can implement it without asking permission or paying a licence, which is why it turns up in so many programs and why files written twenty years ago still open.

Nothing is thrown away

KML stores its content exactly. Saving it again changes nothing, so it can be opened, edited and re-saved as often as you like without accumulating damage — which is what makes it a working format rather than a delivery one.

What opens KML

Google Earth, QGIS and ArcGIS read it, and so do most programs of the same kind.

If a file will not open, the format is rarely the problem — it is more often that the program predates it. Converting to something older is the reliable way past that, and it is what the rest of this site is for.

Opening it in a browser

No browser reads it.

That is the single most common reason to convert it: not that the format is bad, but that the place you want to show the file cannot read it.

It is a working format

KML is meant to be opened and changed. Keep the file in this format for as long as the work is going on, and export from it whenever a finished copy is needed.

The facts, in one place

Converting KML to something else

• KML to CSV
• KML to GPX
• KML to KMZ
• KML to TCX

Converting something else to KML

• GPX to KML
• KMZ to KML
• TCX to KML

Formats worth considering instead of KML

• Zipped KML
• GPS Exchange Format