KML vs GeoJSON: Head-to-Head Comparison
KML and GeoJSON are both popular open geospatial formats, but they serve very different purposes. KML was built for Google Earth visualisation with rich styling and overlays. GeoJSON was built for the web — lightweight, JSON-native, and perfect for Leaflet, Mapbox, and APIs. Here is a direct comparison to help you choose.
Bottom line
Choose KML when you need rich styling or Google Earth compatibility. Choose GeoJSON for web mapping, APIs, and data pipelines.
KML vs GeoJSON: feature comparison
| Feature | KML | GeoJSON |
|---|---|---|
| Format type | XML text | JSON text |
| Primary use | Visualisation (Google Earth) | Data exchange & web mapping |
| Styling support | Yes (colors, icons, labels) | No (styling handled by the app) |
| Coordinate system | WGS 84 only | WGS 84 only |
| Google Earth | Native | Via plugin |
| Leaflet / Mapbox GL | Limited | Native |
| GitHub map preview | No | Yes |
| File size | Larger (XML overhead) | Smaller |
| Human readable | Yes | Yes |
| Polygon support | Yes | Yes |
| Multi-layer | Yes (via folders) | No (single FeatureCollection) |
| OGC standard | Yes (OGC KML) | Yes (RFC 7946) |
KMLWhen to use KML
- Sharing styled maps in Google Earth Desktop or Google Earth Web
- Importing annotated data into Google My Maps
- Field work with Avenza Maps or other KML-compatible mobile apps
- Maps with custom icons, color-coded features, or animated time data
- Presentations where geographic data needs visual styling
GeoJSONWhen to use GeoJSON
- Web mapping with Leaflet, Mapbox GL JS, or deck.gl
- Automatic GitHub map previews for geospatial repositories
- REST APIs that serve geographic data to clients
- Data pipelines in Python (geopandas), JavaScript, or R
- Collaboration via text editors, git, and human-readable diffs
Convert between KML and GeoJSON
Frequently asked questions
Q.Can I convert KML to GeoJSON?
Yes. Maparz converts KML to GeoJSON instantly — upload your .kml or .kmz file and download the result in seconds. The geometry and attributes are preserved; KML-specific styling is not carried over to GeoJSON.
Q.Which format is better for Leaflet or Mapbox?
GeoJSON is the native format for both Leaflet and Mapbox GL JS. Both libraries can load a GeoJSON file directly with a single function call. KML requires an additional plugin.
Q.Is GeoJSON always in WGS 84?
Yes. Per RFC 7946, all GeoJSON coordinates must be in WGS 84 (EPSG:4326). KML also uses WGS 84 exclusively, so both formats share the same coordinate system.
Q.Which format is smaller?
GeoJSON is generally smaller than equivalent KML because JSON has less markup overhead than XML. KMZ (compressed KML) can match or beat GeoJSON in file size for large datasets.