KML to GeoJSON Converter: Google Earth for Web Maps

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How to use this tool

Drop a .kml file above and press Convert to GeoJSON. What comes back is a single text file that any web mapping library can read directly, which is the usual reason for this conversion.

If your file is a .kmz, use the KML and KMZ Viewer to look inside it first, or convert the .kml you extract from it.

What carries across cleanly

Geometry and coordinates transfer exactly, including the coordinate order, since both formats write longitude before latitude. A KML MultiGeometry becomes a GeoJSON GeometryCollection, keeping every part rather than only the first.

Names and descriptions become ordinary properties. ExtendedData values become properties too, keeping their names in full, which is a relief after the ten character limit a shapefile would have imposed.

What has nowhere to go

GeoJSON is geometry plus a bag of properties. Everything else in a KML is presentation, and presentation does not travel.

Icons, line colours, fill transparency and label styles have no equivalent at all and are dropped. If the colours in your KML carry meaning, and they usually do, write that meaning into a property before converting or it is gone.

Ground overlays and screen overlays are images draped on the map rather than vector data, so they are dropped as well.

Folders are the interesting case. A KML nests folders to mean something, usually a phase, a contractor or a survey date, and GeoJSON has no folders at all. Rather than discarding that, this tool writes the full folder path into a property, so a placemark inside Boreholes inside Site Survey arrives carrying Site Survey / Boreholes. It is the only record that survives, and most converters throw it away.

A worked check you can repeat on paper

Load the sample and convert it, then open the result. The sample has three placemarks inside a folder structure.

• Count the objects in the features array. There should be three.
• Look at the properties on the first one. You should see name, folder and depth.
• The folder value should read Site Survey / Boreholes, with the full path rather than just the innermost folder name.

That third check is the one worth doing on any converter you are evaluating. A tool that gives you only Boreholes has lost the parent, and a tool that gives you nothing has lost the structure entirely. On a file with four phases and three contractors, that column is the difference between data you can group and a flat list of points.

Mistakes that catch people out

Expecting the styling to appear in your web map. It will not. Style by property in your mapping library instead.

Assuming a MultiGeometry survives elsewhere. Many parsers read only the first part of one. This tool reads all of them, and it is worth checking the feature and vertex counts against the original.

Forgetting that GeoJSON has no projection field. It is WGS84 by definition, which is fine here because KML is too.

Sending very large GeoJSON uncompressed. It is verbose and compresses well.

Losing the description formatting. A KML description often holds HTML for the balloon. It comes across as a property containing that markup, which is text rather than something your map will render.

Related Calculators and Reference

Google Earth to a web map is one of the most common journeys in this family.

• GeoJSON to KML Converter for the return journey, back into Google Earth.
• GeoJSON Viewer for drawing and checking the GeoJSON you produced.
• KML and KMZ Viewer for reading the KML first, including its folder structure.
• KML to Shapefile Converter for taking the same data into GIS as a shapefile instead.
• CSV to KML Converter for building a KML from a spreadsheet in the first place.
• The Open Geospatial Consortium KML standard is the authority on what a KML placemark can carry.