You've been sent a .kmz file and double-clicking it does nothing useful. Here's exactly what a KMZ is, how to open it, and how to turn it into whatever you actually need.
A KMZ is a zipped KML — a ZIP archive that contains a KML document (usually named doc.kml) plus any icons, images or overlays it references. Google Earth exports KMZ by default because it's smaller and keeps everything in one file. That's also why opening it in Notepad shows gibberish: you're looking at compressed binary, not text.
Unzip a typical KMZ and you'll usually find a small, predictable structure: doc.kml at the root holding all the geometry and attributes, and often a files/ or images/ folder containing custom pin icons, logos, or ground-overlay imagery. The KML is plain XML — human-readable text you can open in any editor. Everything else is just supporting media.
Two reasons: size and portability. KML is verbose XML that compresses extremely well — a 10 MB KML often becomes a 1 MB KMZ. And because custom icons travel inside the archive, emailing a single KMZ guarantees the recipient sees your map exactly as you designed it, with no broken image links.
If you just want to view the data, double-click the .kmz and it opens in Google Earth (desktop or the web version at earth.google.com). The placemarks, paths and imagery appear on the globe. This is the quickest route when you don't need the underlying data in another program.
Google Earth Pro for Windows/Mac opens KMZ natively and is free. Google Earth for web (earth.google.com) works too — use File → Import KML file from the left-hand menu. On Android and iOS the Google Earth app can open a KMZ you've saved to your device or received as an attachment, though very large files may struggle on mobile.
Both major GIS packages read KMZ directly. In QGIS, use Layer → Add Layer → Add Vector Layer and point it at the .kmz — no unzipping needed. In ArcGIS Pro, the KML To Layer geoprocessing tool converts it into a file geodatabase feature class. If you plan to edit or analyse the data, converting it to a shapefile or GeoPackage first is usually less painful than working with KML directly.
Because a KMZ is just a ZIP, you can rename it and unzip it:
file.kmz to file.zip.doc.kml — the readable KML document — plus any images.Now you have the raw KML you can open in a text editor or load into GIS software.
If Windows hides file extensions you may end up with file.kmz.zip or nothing happening at all. Turn on File name extensions in the Explorer View tab first. Alternatively, skip renaming entirely: 7-Zip, WinRAR and Keka can all open a .kmz directly with Open archive, and macOS users can run unzip file.kmz in Terminal.
The extracted doc.kml is XML, so a text editor with syntax highlighting (VS Code, Notepad++, Sublime) makes it far easier to read. You can hand-edit placemark names, descriptions and coordinates. Just be careful with the coordinate order — KML writes longitude first, then latitude, which is the reverse of how most people say it.
Most of the time you don't want to view the KMZ — you want the data somewhere else: a spreadsheet, a shapefile for GIS, or plain KML. The fastest way is to convert it right in your browser, with nothing uploaded:
Choose by what you're going to do next. Analysing or editing in desktop GIS? Go to Shapefile or GeoPackage — GeoPackage if your field names are longer than ten characters, since shapefiles truncate them. Building a web map? GeoJSON is the native currency of Leaflet and Mapbox. Just need a list of coordinates for a report or a colleague? CSV or Excel. Loading onto a handheld GPS? GPX.
Most free online converters upload your file to a server you know nothing about. If the KMZ contains client sites, protected habitats, survey points or anything else you'd rather not hand over, that's a genuine problem. Browser-based conversion runs the whole process locally using WebAssembly — the file never leaves your machine, which also means it works offline once the page has loaded.
KMZ files from Google Earth or My Maps often store their attributes inside each placemark's popup (an HTML table or ExtendedData). A good converter lifts those into proper columns so your shapefile or CSV has real fields — not one blob of HTML. That's the difference between usable data and a mess, so check your output's attribute table after converting.
After converting, open the attribute table (in QGIS: right-click the layer → Open Attribute Table) and confirm three things: the row count matches the number of placemarks you expected, the columns are real named fields rather than one long description string full of HTML tags, and the features actually land in the right place on the map.
Usually the placemarks exist but the view isn't there. In Google Earth, right-click the layer in Places and choose Zoom to. If it's still blank, the file may only contain a network link pointing at a server that's no longer serving data.
Coordinates of 0,0 — "Null Island" — mean the latitude and longitude fields were empty or unparsed. If you converted from a spreadsheet, the coordinate columns probably weren't picked up correctly.
Accented characters turning into question marks is a text-encoding mismatch. KML is UTF-8 by definition, so make sure whatever you export to also uses UTF-8 — for shapefiles that means a .cpg file alongside the .dbf.
A KMZ is a ZIP archive, so you can rename it to .zip and extract it, or open it directly with 7-Zip or Keka. Inside you'll find doc.kml, which is plain XML you can read in any text editor. QGIS and ArcGIS also open KMZ files directly, and you can convert one to CSV, Shapefile or GeoJSON in your browser without installing anything.
KML is an uncompressed XML text file. KMZ is a ZIP archive containing that KML plus any icons or overlay images it references. They hold the same geographic data — KMZ is simply smaller and bundles supporting files, which is why Google Earth exports it by default.
Yes, via Google My Maps. Create a new map, click Import on a layer, and upload the KMZ. Note that My Maps has feature limits per layer, so very large KMZ files may need splitting or converting first.
Not directly — Excel can't read the zipped XML. Convert the KMZ to CSV or XLSX first; the placemark names, coordinates and any popup attributes then become ordinary spreadsheet columns.
It depends entirely on the converter. Most send your file to a remote server. If the data is sensitive — client sites, survey points, protected locations — use a converter that runs in your browser, where the file is processed locally and never uploaded.
The most common causes are that the attributes were stored in the placemark popup as HTML and were dropped, or the source had no usable geometry. Check the attribute table after conversion: you should see real named columns and the expected number of rows, not a single description field full of HTML.