What is the KMZ file format?
Files with the .kmz extension are used by Google Earth and other geo-spatial applications to store and share map locations and geographic data. The format was developed by Keyhole, Inc. and, following Google's acquisition of that company in 2004, became the backbone of Google Earth's shareable map files. The underlying KML specification was later adopted as an open standard by the Open Geospatial Consortium (OGC) in 2008.
A .kmz file is a ZIP archive comprised of a primary .kml document - by convention named doc.kml and placed in the root folder - plus any referenced assets such as custom icons, images, ground overlays or 3D models. All content is packed using the DEFLATE compression algorithm, which keeps file sizes small while maintaining broad compatibility. Additional assets are stored in sub-folders within the archive. You can rename a .kmz file to .zip and open it with any archive manager to inspect its contents directly.
.kmz files may contain:
- named placemarks with geographic coordinates (longitude, latitude and optional altitude in WGS 84)
- polygon and path overlays, including image ground overlays
- 3D model data referenced as COLLADA
.daefiles - network links that point to remote
.kmzor.kmlresources
Because geographic data, imagery and annotations can all be packed into a single portable file, .kmz is widely used for distributing datasets, tour routes and custom map layers. The data can also be opened in any geo-spatial application that supports KML encoding - including QGIS, Global Mapper and Google My Maps - not only in Google Earth.
Security & safety
RISK: LOWThe KML inside a KMZ is plain XML with no executable code, so the map data itself is safe to open. Two cautions: a <NetworkLink> element can make a KMZ automatically fetch remote content from a URL when opened (a privacy/tracking vector) - be wary of KMZ from untrusted sources; and shared map data can be privacy-sensitive (a route or set of pins can reveal a home address or routine). Because a KMZ is a ZIP, the usual advice about only unzipping archives from people you trust applies.
Format details
in a nutshellPrograms that open KMZ files
Windows5 apps
7-Zip
Open-source Right-click > Open archive (or rename .kmz to .zip) to extract doc.kml and the bundled images. 
Global Mapper
Paid Professional GIS app; File > Open to load KMZ and convert between many geospatial formats. 
Google Earth Pro (desktop)
Free File > Open and select the .kmz - it loads onto the globe. Free for everyone since 2015.
Google Earth (web)
Free earth.google.com > menu > Projects > Open > Import KML/KMZ file. No install. 
QGIS
Open-source Layer > Add Vector Layer, pick the .kmz to view it as GIS data and convert to other formats. 
macOS2 apps
QGIS
Open-source Add the .kmz as a vector layer to view and convert the map data (Apple silicon and Intel builds). 
Linux3 apps
GPSBabel
Open-source Read the KMZ and convert it to GPX and dozens of GPS formats (command-line/GUI). 
Android1 app
Google My Maps
Free Create a new map > Import, upload the .kmz to view and edit pins/lines/areas in the browser. Technical details
deep spec| Container format | ZIP archive with DEFLATE compression |
| Internal root document | `doc.kml` placed in the archive root by OGC/Google convention |
| MIME type | `application/vnd.google-earth.kmz` |
| Magic bytes | `50 4B 03 04` at offset 0 - standard ZIP "PK" local file header |
| Coordinate reference system | WGS 84 (EPSG:4326) - longitude, latitude and optional altitude |
| Supported geometry types | Point, LineString, LinearRing, Polygon, MultiGeometry, Model |
| 3D model format | COLLADA (`.dae`) files referenced from KML; limited to static geometry |
| Overlay types | GroundOverlay, ScreenOverlay, PhotoOverlay |
| Network links | `<NetworkLink>` elements can reference external KMZ/KML URLs for live or auto-refreshed data |
| Altitude modes | `clampToGround`, `relativeToGround`, `absolute` |
| Style support | Inline and shared styles (`<Style>`, `<StyleMap>`) for icons, lines and polygon fills |
| File inspection | Rename `.kmz` to `.zip` to unpack and read constituent files with any archive tool |
| KML namespace inside | KML 2.2 XML namespace `http://www.opengis.net/kml/2.2` |
| Asset sub-folder convention | `doc.kml` at root; images and models in named sub-folders (e.g. `files/`) |
| Tour and animation support | `<gx:Tour>` and `<gx:FlyTo>` elements enable scripted flythrough tours in Google Earth |
| Text encoding | UTF-8 - KML is an XML dialect; ZIP entry names also use UTF-8 |
| Released | 2004 (Google Earth); KML 2.2 adopted as an OGC standard in 2008 |
| Open standard | Yes · royalty-free |
| Specification | www.ogc.org |
KMZ conversions
Community Q&A
asked by usersNo questions yet - be the first to ask about KMZ files.
