Convert GML to KML Online — Free GIS Converter

GML datasets from government portals and WFS services often contain valuable spatial information that non-GIS stakeholders need to visualize — converting to KML makes that data immediately accessible in Google Earth and Google My Maps without requiring any GIS software.

Why convert GML to KML?

GML is a technically correct but practically inaccessible format for anyone outside the GIS profession. When you need to share spatial data from a WFS service or INSPIRE portal with planners, executives, journalists, or the general public, KML is the clear choice — Google Earth is free, widely installed, and presents geospatial data visually without requiring any GIS knowledge. Converting GML to KML also handles the CRS conversion automatically: GML can be in any coordinate system, while KML always uses WGS 84, so the reprojection is part of the conversion rather than a separate step. The result is a file that anyone with Google Earth or Google My Maps can open and explore immediately.

Why use geodata.plus

• Free tier includes 3 conversions per month with no account required
• Automatic CRS detection from the GML srsName attribute and reprojection to WGS 84 for KML compliance
• Optional reprojection to custom EPSG for intermediate processing before KML export
• Entirely browser-based — no QGIS, GDAL, or Google Earth Pro required to perform the conversion
• Encrypted upload (TLS); files stored in Cloudflare R2, automatically deleted after 2 days (free) or 7 days (Pro)
• GML feature attributes are written to KML <description> balloon content for human-readable display

How it works

1. Upload your .gml file to geodata.plus
2. geodata.plus reads the GML schema and detects the source CRS from srsName attributes
3. Select KML as the output format; coordinates are automatically reprojected to WGS 84
4. Download your .kml file and open it in Google Earth or import it into Google My Maps

GML format

GML (Geography Markup Language) is an OGC XML encoding standard used by WFS services and the EU INSPIRE spatial data infrastructure. GML can use any coordinate reference system and supports a rich vocabulary of geometry types, from simple points and polygons to complex curve and surface geometries. GML feature schemas are defined in XSD documents and can include deeply nested attribute structures. While GML is the backbone of institutional spatial data exchange, it requires dedicated parsing libraries and is not accessible to non-technical users.

| Property | Value | |---|---| | Extension | .gml | | Type | Vector, single-file XML | | Coordinate system | Any CRS (declared via srsName) | | Geometry types | Point, LineString, Polygon, Multi- variants, complex curves/surfaces | | Common software | QGIS, ArcGIS, WFS services, EU INSPIRE portals, government systems |

KML format

KML (Keyhole Markup Language) is an OGC-adopted XML standard developed by Google for geographic visualization. All KML coordinates are in WGS 84 (EPSG:4326). KML's distinguishing feature is its styling model: <Style> elements control line color, fill opacity, and icon imagery, and <description> elements provide HTML balloon content when features are clicked. KML organizes features into <Folder> and <Document> elements for hierarchical grouping. It is natively rendered by Google Earth, Google Maps (via My Maps), ArcGIS, and QGIS.

| Property | Value | |---|---| | Extension | .kml | | Type | Vector, single-file XML | | Coordinate system | WGS 84 (EPSG:4326) only | | Geometry types | Point, LineString, Polygon, MultiGeometry | | Common software | Google Earth, Google Maps, ArcGIS, QGIS |

Frequently asked questions

GML supports complex curve geometries like arcs and splines. How does KML handle these after conversion? KML does not support true mathematical curves. geodata.plus linearizes any arc or spline geometry from GML into densified LineString or Polygon approximations before writing KML. The visual result in Google Earth closely matches the original curve geometry, but it is represented as a series of short straight segments rather than a true curve.

Will my GML feature attributes be visible when I click a feature in Google Earth? Yes. geodata.plus writes GML feature properties as HTML table content inside each KML Placemark's <description> element. When you click a feature in Google Earth, a balloon pops up showing the feature's attribute names and values from the original GML in a readable table format.

My GML file uses a national CRS like SWEREF99 or RD New. Will the conversion handle this automatically? Yes. geodata.plus reads the srsName from the GML geometry elements to identify the source CRS, then performs a precise coordinate transformation to WGS 84 before writing the KML. The output coordinates will be accurate geographic coordinates in the correct global position, regardless of what national or projected CRS the GML used.