How to convert between KML and KMZ
- Drop a .kml or a .kmz; the converter reads which one it is and offers the other format.
- There is nothing to set: a KML is zipped as it is, and from a KMZ the main document inside is extracted.
- Convert and download, then open the result in Google Earth or open the KML in a text editor.
What changes when you convert between KML and KMZ
| What | KML → KMZ | |
|---|---|---|
| Geometry | Kept | Points, lines and polygons are preserved exactly, including multi-part shapes. |
| Attributes | Kept | Every column and full field name moves from KML into KMZ untouched. |
| Styling & labels | Kept | Both formats store Google Earth styling, so colors, icons and description balloons carry across unchanged. |
| Coordinate system | Kept | Both formats are fixed to WGS84 longitude/latitude (EPSG:4326), so the coordinates are copied across without any reprojection. |
| Elevation (Z) | Kept | 3D Z values carry from KML into KMZ wherever the source records them. |
| File structure | Kept | One compact .kmz (a zipped KML), easy to email and quick to open in Google Earth. |
| KMZ back to KML | Changes | Unpacking a KMZ hands you the same document as readable XML. Images, custom icons and ground overlays that were packed inside the archive stay behind, because a plain .kml cannot carry files; placemarks that pointed at them fall back to default icons. |
Why convert between KML and KMZ?
KML is plain XML that Google Earth reads directly, which makes it easy to edit, search and diff, but a detailed file with thousands of placemarks grows large. KMZ is the same document zipped into one archive, often with icons and overlays packed beside it, so it is what Google Earth exports by default and what people email. The two directions serve two moments in the same job: zip to KMZ when a map is finished and has to travel as a single small attachment, and unpack to KML when you need to fix a label by hand, keep the file in version control, or feed a tool that reads KML but rejects the zipped wrapper.
Coordinate system handling
Neither direction touches the coordinate system. KML and KMZ are both fixed to WGS84 longitude and latitude (EPSG:4326) by the Google Earth specification, so the numbers inside the document are copied exactly as they are.
If a KML looks misplaced in Google Earth, the error was already in the file before conversion, usually latitude and longitude written in the wrong order. KML lists longitude first, then latitude, then an optional altitude.
What to check when converting between KML and KMZ
This is a packaging step, so geometry, attributes, styling and coordinates are all kept; the thing to watch is files. Going from KML to KMZ, only the document is read: icons stored as local files beside the .kml are not packed into the archive, while icons referenced by a web address keep working. Going from KMZ to KML, images, custom icons and ground overlays inside the archive stay behind, and placemarks that pointed at them fall back to default icons. Keep the original file around whenever those bundled assets matter.
Troubleshooting KML and KMZ
- Custom icons disappeared after converting. Icons stored as local files were never inside the document, so they were not packed into the KMZ, or they were left behind when the KMZ was unpacked. Host the icons at a web address and reference them by URL, or keep the original file alongside the converted one.
- Google Earth shows the layer but no ground overlay. Overlay images live inside the KMZ archive, not in the KML text. After KMZ to KML the overlay element still exists but its image is gone, so Google Earth draws nothing there. Use the original KMZ for overlays.
- The KMZ arrives as a .zip or will not open from a mail app. Some mail and chat apps treat a .kmz as a plain zip and rename or block it. Rename the attachment back to .kmz, share it through a file link, or send the KML instead.
- I dropped a file and the wrong output was offered. The output follows the file you dropped: a .kmz is offered KML and a .kml is offered KMZ. If a file was renamed by hand, check its real extension, or pick the output you want from the buttons before converting.
About the formats
KML holds placemarks, paths, polygons, folders and styling as plain XML that opens in any text editor. KMZ is that same document inside a ZIP archive, usually as doc.kml at the root, with an optional folder of icons and overlay images beside it. Converting between them is a packaging step rather than a translation: the geometry, the labels and the folder tree are identical on both sides, which is why Google Earth reads either one the same way.
Frequently asked questions
Why is my KMZ not much smaller than the KML?
Compression works on repeated text, so a file that is mostly long coordinate lists shrinks less than one full of styles and descriptions. The site's 10,000-point benchmark turned a 5.18 MB KML into a 0.33 MB KMZ, about 16 times smaller, and geometry-heavy files sit below that ratio.
Can I just rename a .kmz to .zip and unzip it myself?
Yes. A KMZ is an ordinary ZIP archive with doc.kml inside, plus any bundled images. The converter does the same thing in the browser and hands you the document directly, which is quicker when you only want the KML.
My KML looks misplaced after converting, so did the conversion move the coordinates?
No. Coordinates are copied exactly in both directions, so the error was already in the file, usually latitude and longitude written in the wrong order. KML lists longitude first, then latitude.
Why would I unpack a KMZ instead of keeping it?
The KML inside is plain XML, so a text editor lets you fix names, coordinates and styling by hand, and it diffs cleanly in version control. Some tools also read KML but reject the zipped wrapper, and the unpacked file stays fully readable in Google Earth, QGIS and ArcGIS.
Related converters
This page runs in both directions, so drop a KMZ to get the KML back out. You can also send the same data to a shapefile or a CSV of coordinates. The complete set is on the KML & KMZ converter hub.
Ready to convert?
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