File Conversion
Convert KML to FGB online
Convert Keyhole Markup Language (KML) — the Google Earth and Google Maps format — into FlatGeobuf, which is a fast, streamable binary format built for large datasets. Drop your KML file below, FGB is already selected as the output, and download the result. Everything runs in your browser and the cloud; you never install anything.
Upload your file
Drag and drop it into the converter below — no account needed to start.
Convert in the cloud
MapGO detects the format and produces your download in seconds.
Download & keep it
Files are deleted automatically after 48 hours.
Files are deleted automatically after 48 hours. Your files are never shared.
Why convert KML to FGB with MapGO?
Most online converters take one file and hand back one file. MapGO is built on a real geospatial engine, so a single upload can do more:
- Several outputs in one upload — tick FGB and any other formats you need; every selected format is delivered from the same file.
- Files up to 5 GB — far beyond the browser-based converters that choke past a few hundred megabytes.
- Reproject while you convert — set a source and target EPSG code and the coordinate system is changed during the conversion, no second tool needed.
- Private by default — files are deleted automatically after 48 hours.
KML vs FGB at a glance
| KML | FGB | |
|---|---|---|
| Typical use | Google Earth / Google My Maps visualisation and sharing placemarks | Large datasets streamed to web maps; cloud-native data pipelines |
| Size on disk | Verbose XML; the zipped KMZ variant shrinks it considerably | Compact binary with a built-in spatial index |
| Attribute support | Styling-first — data lives in ExtendedData and is easy to lose | Full attribute tables |
| Software support | Google Earth/Maps and most GIS tools | GDAL/QGIS, plus web libraries via the flatgeobuf JS package |
| Web-friendliness | Good inside the Google ecosystem; niche elsewhere | Excellent — streams over plain HTTP range requests |
Other ways to convert KML to FGB
You don't need an online tool for this. If you have GDAL installed, one command does it:
ogr2ogr -f "FlatGeobuf" output.fgb input.kmlIn QGIS (free): open your KML via Layer → Add Layer, then right-click the layer → Export → Save Features As… and pick FGB as the format.
The MapGO converter above is for when you don't want to install anything, need to convert to several formats at once, or are handling files too large for a desktop machine — drop the file and download the result.
KML to FGB: frequently asked questions
Is the KML to FGB converter free?
Yes — new accounts get free conversion credits to start, and every paid plan converts unlimited files within its size limit. There is nothing to install; the whole KML-to-FGB conversion runs in the cloud.
Is my data kept private?
Conversion is fully automated and your file is never shared. Files are deleted automatically after 48 hours. Download your FGB result and it's yours to keep.
What does the FGB output contain?
You get a clean FlatGeobuf file with your geometry and attributes preserved, ready to open in the tools that read FGB.
What happens to the attributes stored in my KML?
KML keeps attribute data in ExtendedData elements (and sometimes in free-text descriptions). Structured ExtendedData fields are mapped to real attribute columns in the output; icons and styling are display settings rather than data, so they don’t carry over.
What is FlatGeobuf actually good for?
It is a binary format with a built-in spatial index that web maps can stream over plain HTTP — the browser fetches only the features in view, no tile server required. Leaflet, MapLibre and OpenLayers read it via the flatgeobuf JavaScript package.
Can I convert FGB back to KML?
Yes — use our FGB to KML converter for the reverse direction. MapGO supports conversions in both directions between these formats.