Convert WGS84 coordinate system to GCJ02 coordinate system (Mars Coordinate System)
Use standard algorithms to ensure conversion accuracy
Support batch conversion of large numbers of coordinates
Support text, CSV, JSON and other formats
Convert coordinates from WGS84 system to GCJ02 system
Paste your WGS84 coordinates into the input box — one point per line in "latitude, longitude" order. You can paste a single GPS reading or an entire track log of thousands of points.
Click the Convert button and the GCJ02 offset algorithm is applied to every line at once. Points outside mainland China are returned unchanged, since the Mars Coordinate System only applies within China.
Copy a single result with one click, or download the whole batch as CSV or JSON. Everything runs locally in your browser — free, with no upload and no sign-up.
AGPS devices record in WGS84, but maps in China (Amap, Tencent, Baidu) render in GCJ02, a deliberately shifted national coordinate system. The offset varies by location and is typically 100-700 meters. Converting WGS84 to GCJ02 before plotting removes this displacement.
AThe GCJ02 offset only applies to mainland China, so points abroad are returned exactly as entered. Feeding foreign coordinates through the offset formula would corrupt them, so the tool detects and skips them.
AThe tool uses the publicly known offset algorithm, which matches what domestic map services display to within roughly 1-2 meters for most locations. That is ample for map display, navigation, and POI placement, but it is not a certified surveying-grade transformation.