Definition and role in GIS
GCJ-02 is based on WGS84 but applies a national offset algorithm. Coordinates plotted as WGS84 on a GCJ-02 basemap (or the reverse) will appear shifted—often by tens to hundreds of meters. For GIS pipelines that mix GPS field data with Chinese web tiles, you must convert between datums explicitly.
GCJ-02 vs WGS84
WGS84 describes positions relative to the global GPS reference ellipsoid without the China-specific offset. GCJ-02 adds that offset so that raw GPS points do not line up with encrypted map graphics. Use WGS84 for international exchange, scientific GPS, and many global datasets; use GCJ-02 when publishing or picking points that must match GCJ-based map APIs.
Typical use cases
Common cases include aligning survey CSVs with street maps from Chinese providers, debugging location APIs, and preparing batch files for apps that only accept GCJ-02. Our coordinate tool supports batch conversion among WGS84, GCJ-02, BD-09, and many EPSG definitions.
FAQ
- Is GCJ-02 the same as WGS84?
- No. They are related datums but offsets differ; you need a conversion algorithm to move between them accurately.
- Why do my GPS points look wrong on a Chinese basemap?
- The basemap is likely drawn in GCJ-02 while your file is WGS84 (or the opposite). Convert to the same system as the map provider.
- Does GCJ-02 apply in Hong Kong or Taiwan?
- Mainland rules drove GCJ-02 adoption on many Chinese services; other regions may use WGS84 or different local policies. Always check your map provider documentation.
- How do I convert GCJ-02 to CGCS2000?
- Open the coordinate converter with source GCJ-02 and target EPSG:4490 (CGCS2000), or follow our GCJ-02 to CGCS2000 method guide. Processing stays in your browser.