Guide

KML and KMZ Files: Google Earth's Geographic Markup Language

PC By Pablo Cirre • Updated May 7, 2026

What Are KML and KMZ?

KML — Keyhole Markup Language — is an XML-based file format for expressing geographic annotations and visualizations in two-dimensional maps and three-dimensional Earth browsers. Originally created by Keyhole Inc. for its EarthViewer 3D application, KML became a household name when Google acquired Keyhole in 2004 and integrated KML support into Google Earth. In 2008, the Open Geospatial Consortium (OGC) adopted KML as an international standard (OGC KML 2.2), cementing its place alongside GeoJSON and Shapefile as a cornerstone of geospatial data exchange.

KMZ is a ZIP-compressed archive containing one or more KML files plus any referenced assets — icon images, embedded textures, COLLADA 3D model files. KMZ is the preferred exchange format because it bundles everything into a single portable container and reduces size by 50–80% compared to uncompressed KML with linked external images.

Core KML Elements

KML documents describe geographic features using a hierarchy of XML elements.

Placemarks

The fundamental annotation unit — a location with geometry and optional description:

<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2">
  <Document>
    <name>My Locations</name>
    <Placemark>
      <name>Eiffel Tower</name>
      <description>Built for the 1889 World's Fair in Paris.</description>
      <Point>
        <coordinates>2.2945,48.8584,324</coordinates>
      </Point>
    </Placemark>
  </Document>
</kml>

Coordinates are specified as longitude,latitude,altitude — note the order. Longitude first. Altitude is optional and in meters above the reference surface defined by altitudeMode.

Geometry Types

Type	KML Element	Use Case
Point	`<Point>`	Location markers, pins, waypoints
Line	`<LineString>`	Paths, routes, pipelines, roads
Polygon	`<Polygon>`	Areas, administrative boundaries, zones
Multi-geometry	`<MultiGeometry>`	Compound shapes combining the above
Model	`<Model>`	3D objects referencing COLLADA .dae files

Altitude Modes

<Point>
  <altitudeMode>relativeToGround</altitudeMode>
  <coordinates>-73.985,40.748,443</coordinates>
</Point>

Mode	Behavior
`clampToGround`	Feature pressed flat to terrain surface (default)
`relativeToGround`	Altitude above the local terrain at that lat/lon
`absolute`	Altitude above WGS84 ellipsoid sea level
`clampToSeaFloor`	Clamped to ocean floor (gx: extension)

Styles and Icons

KML separates geometry from presentation using named Style elements:

<Style id="blueMarker">
  <IconStyle>
    <color>ffff0000</color>
    <scale>1.3</scale>
    <Icon>
      <href>http://maps.google.com/mapfiles/kml/paddle/blu-circle.png</href>
    </Icon>
  </IconStyle>
  <LabelStyle>
    <color>ffffffff</color>
    <scale>0.9</scale>
  </LabelStyle>
  <LineStyle>
    <color>ffff0000</color>
    <width>4</width>
  </LineStyle>
  <PolyStyle>
    <color>7fff0000</color>
    <fill>1</fill>
    <outline>1</outline>
  </PolyStyle>
</Style>

<Placemark>
  <styleUrl>#blueMarker</styleUrl>
  <Point><coordinates>2.2945,48.8584,0</coordinates></Point>
</Placemark>

Colors in KML use AABBGGRR order (alpha, blue, green, red) — the inverse of web hexadecimal RGB. A fully opaque red is ff0000ff; a 50%-transparent red is 7f0000ff. The alpha channel ff = fully opaque, 00 = fully transparent.

StyleMap elements allow separate styles for normal and highlighted states, enabling hover effects in Google Earth.

NetworkLink: Dynamic Data Feeds

NetworkLink allows KML documents to load remote KML/KMZ data on demand or on a timer:

<NetworkLink>
  <name>Live Earthquake Feed</name>
  <Link>
    <href>https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_hour.kml</href>
    <refreshMode>onInterval</refreshMode>
    <refreshInterval>300</refreshInterval>
  </Link>
</NetworkLink>

This enables real-time data overlays — earthquake alerts, flight tracking positions, weather radar — all pulling from a URL that regenerates every N seconds. NetworkLink is the mechanism behind Google Earth's live data layers: traffic, weather, borders, and community pins. A single KML file can chain multiple NetworkLinks, each pointing to different servers with different refresh rates.

viewRefreshMode combined with viewRefreshTime triggers reloads whenever the camera view changes — critical for large datasets loaded in spatial tiles, where you only request data for the current viewport.

GroundOverlay: Raster Image Draping

Draping raster images (satellite imagery, custom maps, heatmaps, historical maps) over the 3D terrain:

<GroundOverlay>
  <name>Flood Extent Map — 2024-03-15</name>
  <color>aaffffff</color>
  <Icon>
    <href>flood_extent.png</href>
    <viewBoundScale>0.75</viewBoundScale>
  </Icon>
  <LatLonBox>
    <north>40.850</north>
    <south>40.700</south>
    <east>-73.900</east>
    <west>-74.050</west>
    <rotation>0</rotation>
  </LatLonBox>
</GroundOverlay>

The <color> element controls global opacity (aa = ~67% transparent). GroundOverlay is used heavily in emergency management to drape aerial survey imagery and damage assessment maps over Google Earth for situational awareness during disasters.

Folders, Playlists, and Tours

Folder elements organize features hierarchically — exactly like a file system. Google Earth displays these as collapsible layers in the Places panel.

gx:Tour elements (from the Google Extensions namespace) define animated fly-through sequences:

<gx:Tour>
  <name>European Capitals Tour</name>
  <gx:Playlist>
    <gx:FlyTo>
      <gx:duration>4.0</gx:duration>
      <LookAt>
        <longitude>2.3522</longitude>
        <latitude>48.8566</latitude>
        <altitude>1500</altitude>
        <range>3000</range>
        <tilt>55</tilt>
        <heading>0</heading>
      </LookAt>
    </gx:FlyTo>
    <gx:Wait><gx:duration>2.0</gx:duration></gx:Wait>
  </gx:Playlist>
</gx:Tour>

The gx: namespace prefix indicates Google Extension elements — they are valid in Google Earth but may be silently ignored by strict OGC implementations. Tours are used extensively in journalism, education, and real estate visualization.

Creating and Converting KML

Creating KML with Python using simplekml:

import simplekml

kml = simplekml.Kml()

# Add a point marker
pnt = kml.newpoint(name="Colosseum, Rome")
pnt.coords = [(12.4924, 41.8902, 0)]
pnt.description = "Built between 70–80 AD. Capacity: ~50,000 spectators."
pnt.style.iconstyle.icon.href = (
    "http://maps.google.com/mapfiles/kml/paddle/grn-circle.png"
)

# Add a polygon
pol = kml.newpolygon(name="Approximate footprint")
pol.outerboundaryis = [(12.4915, 41.8896),
                       (12.4935, 41.8896),
                       (12.4935, 41.8910),
                       (12.4915, 41.8910),
                       (12.4915, 41.8896)]
pol.style.polystyle.color = "7f00ff00"   # 50% transparent green

kml.save("colosseum.kml")
kml.savekmz("colosseum.kmz")             # compressed version

Converting between formats with ogr2ogr (GDAL):

# KML → GeoJSON
ogr2ogr -f GeoJSON output.geojson input.kml

# KML → ESRI Shapefile
ogr2ogr -f "ESRI Shapefile" output_folder/ input.kml

# GeoJSON → KML
ogr2ogr -f KML output.kml input.geojson

# Simplify geometry (reduce vertex count, tolerance in map units)
ogr2ogr -f KML simplified.kml input.kml -simplify 0.0001

GDAL's ogr2ogr is the universal Swiss Army knife for vector format conversion. GDAL 3.x includes KML read/write support enabled by default, recognizing both .kml and .kmz extensions automatically.

KML vs GeoJSON

Feature	KML	GeoJSON
Syntax	XML	JSON
Built-in styling	Yes (IconStyle, LineStyle, PolyStyle)	No (requires external style spec)
3D support	Full (altitude, extrusion, models)	Limited (Z coordinate only)
Google Earth native	Yes	Via conversion
Leaflet / MapboxGL	Plugin needed	Native
OGC standard	Yes (KML 2.2, 2008)	Yes (RFC 7946, 2016)
Typical compression	KMZ (ZIP)	FlatGeobuf / GeoPackage
Streaming/tiling	NetworkLink + Region LOD	Vector tiles (MVT)

GeoJSON has largely displaced KML for web mapping applications — it integrates natively with JavaScript environments, REST APIs, and modern map libraries. KML remains dominant for Google Earth desktop workflows, aerial survey deliverables, FAA airspace filings, and any scenario requiring rich 3D visualization, tour animations, or timed dynamic overlays.

Validating KML

KML 2.2 has a formal XML Schema (XSD) downloadable from OGC:

xmllint --schema ogckml22.xsd --noout yourfile.kml

Common KML errors include:

Coordinate order mistake: writing latitude,longitude instead of longitude,latitude — places Paris in the Atlantic Ocean
Unclosed polygon ring: outer boundary must repeat the first coordinate as the last coordinate
Invalid altitudeMode: typos like relativeToTerrain instead of relativeToGround
Missing namespace declaration: xmlns="http://www.opengis.net/kml/2.2" on the root <kml> element

Google Earth is forgiving of many validation errors; strict OGC implementations reject them outright.

Real-World Applications

Emergency management: FEMA publishes evacuation zone KML files during hurricanes and wildfires; emergency managers load them into Google Earth for field team briefings
Aviation: FAA Temporary Flight Restrictions (TFRs) and drone flight zones are distributed as KML by the FAA's UAS Data Delivery System
Real estate: property boundary overlays and development zone maps for site due diligence and investment analysis
Conservation: WWF, NPS, and IUCN distribute protected area boundary datasets as KMZ for field teams without GIS expertise
Urban planning: city planning departments publish zoning maps, transit corridors, and infrastructure overlays as KML for public consultation
Precision agriculture: field boundary maps, soil sampling grids, and variable-rate application zones distributed to farm equipment via KML

Performance note: Google Earth begins degrading at approximately 10,000 simultaneously visible features. For large datasets, use NetworkLink combined with Region elements and Level of Detail (LOD) settings to load data progressively as the user zooms in.

Related conversions

Frequent conversions across the catalogue:

Frequently Asked Questions

KML is a plain-text XML file describing geographic features. KMZ is a ZIP-compressed archive containing the KML document plus any referenced resources — icon images, embedded textures, COLLADA 3D models. KMZ files are typically 50–80% smaller than equivalent KML with external images, and bundle everything into one portable container. When you save a project from Google Earth with custom icons or linked images, it always exports as KMZ. You can inspect any KMZ by renaming it to .zip and extracting it with any archive tool.

KML is a plain-text XML arquivo describing geographic features. KMZ is a ZIP-compressed archive containing the KML document plus any referenced resources — icon images, embedded textures, COLLADA 3D models. KMZ arquivos são tipicamente 50–80% menor que equivalent KML com external images, e bundle everything em one portable container. When you salvar a project de Google Earth com custom icons ou linked images, it always exports as KMZ. You can inspect any KMZ by renaming it to .zip e extracting it com any archive tool.

KML is a plain-text XML Datei describing geographic features. KMZ is a ZIP-compressed archive containing the KML document plus any referenced resources — icon images, embedded textures, COLLADA 3D models. KMZ Dateien are typically 50–80% kleiner als equivalent KML mit external images, und bundle everything in one portable Container. When you speichern a project von Google Earth mit custom icons oder linked images, it always exports as KMZ. You can inspect any KMZ by renaming it to .zip und extracting it mit any archive tool.

KML is a plain-text XML archivo describing geographic features. KMZ is a ZIP-compressed archive containing the KML document plus any referenced resources — icon images, embedded textures, COLLADA 3D models. KMZ archivos are typically 50–80% más pequeño que equivalent KML con external images, y bundle everything en one portable contenedor. When you guardar a project de Google Earth con custom icons o linked images, it always exports as KMZ. You can inspect any KMZ by renaming it to .zip y extracting it con any archive tool.

On KaijuConverter every file is processed inside an isolated container, encrypted in transit (TLS 1.3) and at rest, and automatically deleted after 60 minutes with multi-pass overwrite. We never train on, share, or analyze user content. For maximum privacy on extremely sensitive material, prefer offline tools (ImageMagick, FFmpeg, LibreOffice) that you control end-to-end.

KML follows the mathematical (X, Y) convention where X = easting = longitude and Y = northing = latitude. This is the standard in GIS and geodesy, and GeoJSON uses the same order. The everyday geographic convention (latitude first) comes from navigation and paper maps. Swapping longitude and latitude is the single most common KML bug — it places features in completely wrong locations, often in the ocean. Always remember: in KML and GeoJSON, coordinates go longitude, latitude, altitude.

KML segue a convenção matemática (X, Y) onde X = easting = longitude e Y = northing = latitude. É o padrão em GIS e geodésia, e GeoJSON usa a mesma ordem. A convenção geográfica do dia a dia (latitude primeiro) vem da navegação e dos mapas em papel. Trocar longitude e latitude é o bug mais comum em KML — coloca os elementos em locais completamente errados, frequentemente no meio do oceano. Lembre-se sempre: em KML e GeoJSON, as coordenadas vão longitude, latitude, altitude.

KML folgt der mathematischen (X, Y)-Konvention, wobei X = Easting = Längengrad und Y = Northing = Breitengrad. Das ist der Standard in GIS und Geodäsie, und GeoJSON nutzt dieselbe Reihenfolge. Die alltägliche geografische Konvention (Breitengrad zuerst) stammt aus der Navigation und Papierkarten. Längen- und Breitengrad zu vertauschen ist der häufigste KML-Bug — er platziert Elemente an völlig falschen Orten, oft mitten im Ozean. Merke immer: in KML und GeoJSON gehen Koordinaten Längengrad, Breitengrad, Höhe.

KML sigue la convención matemática (X, Y) donde X = easting = longitud e Y = northing = latitud. Es el estándar en GIS y geodesia, y GeoJSON usa el mismo orden. La convención geográfica cotidiana (latitud primero) viene de la navegación y los mapas en papel. Intercambiar longitud y latitud es el bug más común en KML — coloca elementos en lugares completamente equivocados, a menudo en mitad del océano. Recuerda siempre: en KML y GeoJSON, las coordenadas van longitud, latitud, altitud.

For 95% of use cases, yes — server-side ImageMagick, FFmpeg and LibreOffice produce identical output to the same tools on your laptop. Desktop software wins for: extremely large files (multi-GB), batch jobs of thousands of files, scripted pipelines, or content too sensitive to upload. KaijuConverter caps at 25 MB per file on the free tier (up to 2 GB on paid plans).

Several strategies: (1) Convert to KMZ — halves file size by ZIP compression. (2) Reduce coordinate precision to 5 decimal places (~1 m accuracy on the equator). (3) Simplify polygon geometry using ogr2ogr -simplify 0.0001 to reduce vertex count. (4) Use NetworkLink to load data in geographic tiles rather than all at once. (5) Replace repeated inline style definitions with shared <Style id="..."> references. For truly massive datasets (millions of features), switch to GeoPackage or vector tiles (MVT) instead of KML.

Several strategies: (1) converter to KMZ — halves tamanho do arquivo by ZIP compressão. (2) Reduce coordinate precision to 5 decimal places (~1 m accuracy no equator). (3) Simplify polygon geometry usando ogr2ogr -simplify 0.0001 to reduce vertex count. (4) usar NetworkLink to load data in geographic tiles em vez de all at once. (5) Replace repeated inline style definitions com compartilhado <Style id="..."> references. para truly massive datasets (millions of features), switch to GeoPackage ou vector tiles (MVT) em vez de KML.

Several strategies: (1) umwandeln to KMZ — halves Dateigröße by ZIP Komprimierung. (2) Reduce coordinate precision to 5 decimal places (~1 m accuracy auf dem equator). (3) Simplify polygon geometry using ogr2ogr -simplify 0.0001 to reduce vertex count. (4) verwenden NetworkLink to load data in geographic tiles rather than all at once. (5) Replace repeated inline style definitions mit shared <Style id="..."> references. für truly massive datasets (millions von features), switch to GeoPackage oder vector tiles (MVT) anstatt KML.

Several strategies: (1) convertir to KMZ — halves tamaño de archivo by ZIP compresión. (2) Reduce coordinate precision to 5 decimal places (~1 m accuracy en el equator). (3) Simplify polygon geometry using ogr2ogr -simplify 0.0001 to reduce vertex count. (4) usar NetworkLink to load data in geographic tiles rather than all at once. (5) Replace repeated inline style definitions con shared <Style id="..."> references. para truly massive datasets (millions de features), switch to GeoPackage o vector tiles (MVT) en vez de KML.

Most format conversions are lossy by design — JPG, MP3, MP4, WebP all discard perceptual data to save bytes. Going through a lossy intermediate compounds the loss. To minimize visible/audible drift: convert from the original master, choose a higher quality setting, and avoid converting back and forth between lossy formats.

Yes. Add <extrude>1</extrude> and <altitudeMode>relativeToGround</altitudeMode> to a Polygon, then set a non-zero altitude value — Google Earth renders the polygon as a 3D prism rising from the ground. For full architectural 3D models, use a <Model> element referencing a COLLADA (.dae) file inside a KMZ archive. Google Earth's built-in city 3D layer uses this mechanism. Note: 3D extrusion displays only in Google Earth desktop and Earth web — not in Google Maps, Leaflet, or most web mapping libraries.

Yes. Add <extrude>1</extrude> e <altitudeMode>relativeToGround</altitudeMode> para um Polygon, then set a non-zero altitude value — Google Earth renders the polygon como um 3D prism rising de the ground. para full architectural 3D models, usar a <Model> element referencing a COLLADA (.dae) arquivo inside a KMZ archive. Google Earth's built-in city 3D layer uses this mechanism. Note: 3D extrusion displays only in Google Earth desktop e Earth web — not in Google Maps, Leaflet, ou most web mapping libraries.

Yes. Add <extrude>1</extrude> und <altitudeMode>relativeToGround</altitudeMode> zu einem Polygon, then set a non-zero altitude value — Google Earth renders the polygon als ein 3D prism rising von the ground. für full architectural 3D models, verwenden a <Model> element referencing a COLLADA (.dae) Datei inside a KMZ archive. Google Earth's built-in city 3D layer uses this mechanism. Note: 3D extrusion displays only in Google Earth desktop und Earth web — not in Google Maps, Leaflet, oder most web mapping libraries.

Yes. Add <extrude>1</extrude> y <altitudeMode>relativeToGround</altitudeMode> a un Polygon, then set a non-zero altitude value — Google Earth renders the polygon como un 3D prism rising de the ground. para full architectural 3D models, usar a <Model> element referencing a COLLADA (.dae) archivo inside a KMZ archive. Google Earth's built-in city 3D layer uses this mechanism. Note: 3D extrusion displays only in Google Earth desktop y Earth web — not in Google Maps, Leaflet, o most web mapping libraries.

Yes — KaijuConverter accepts multiple files in a single drop and returns a ZIP. For very large batches (thousands of files) consider command-line tools or our API: <code>find . -name "*.heic" -exec magick {} {.}.jpg \;</code> or similar one-liners scale to millions of files when run locally.