BD-09 to WGS84 Converter
About BD-09 Coordinate System
BD-09 (Baidu Coordinate System) is a geodetic system developed by Baidu, based on GCJ-02 with additional encryption for use in Baidu Maps and related services.
Baidu developed BD-09 by applying a secondary encryption layer on top of GCJ-02 to further obfuscate coordinates. It is proprietary to Baidu and used exclusively in their mapping ecosystem.
BD-09 is used exclusively in Baidu Maps, Baidu Navigation, and Baidu LBS API. It is the most encrypted coordinate system among Chinese map services.
BD-09 adds a second encryption layer on top of GCJ-02, making it the most heavily obfuscated coordinate system used in China.
Used exclusively within Baidu's mapping platform. If you're developing with Baidu Maps API, all coordinates must be in BD-09 format.
Conversion between BD-09 and other systems relies on reverse-engineered algorithms that provide sub-meter accuracy.
About WGS84 Coordinate System
WGS84 (World Geodetic System 1984) is the global standard geodetic reference system used by GPS. It defines an Earth-centered, Earth-fixed coordinate system and geodetic datum.
Developed by the U.S. Department of Defense in 1984, WGS84 has undergone several refinements (WGS84(G730), WGS84(G873), WGS84(G1150), WGS84(G1762)) to improve accuracy through GPS satellite observations.
WGS84 is the default coordinate system for GPS receivers worldwide. It is used in aviation, maritime navigation, Google Maps, OpenStreetMap, GIS applications, and scientific research.
WGS84 is the native coordinate system of the Global Positioning System (GPS), ensuring direct compatibility with all GPS receivers and satellite navigation systems worldwide.
As the most widely adopted geodetic datum, WGS84 provides a consistent global reference frame for mapping, surveying, and geospatial data exchange across international boundaries.
With continuous refinements, WGS84 achieves centimeter-level accuracy globally, making it suitable for high-precision applications like surveying, drone navigation, and scientific research.
BD-09 to WGS84 Conversion Guide
// BD-09 → WGS84 (two-step inverse)
// Step 1: BD-09 → GCJ-02
x = bdLon - 0.0065
y = bdLat - 0.006
z = √(x² + y²) - 0.00002 × sin(y × 3000 × π / 180)
θ = atan2(y, x) - 0.000003 × cos(x × 3000 × π / 180)
gcjLat = z × sin(θ)
gcjLon = z × cos(θ)
// Step 2: GCJ-02 → WGS84 (using inverse offset)BD-09 to WGS84 is a two-step inverse process. First, reverse the BD-09 polar transformation to get GCJ-02, then apply the GCJ-02 inverse to obtain WGS84 coordinates. This is the most complex reverse conversion among Chinese coordinate systems.
- Enter BD-09 coordinates from Baidu Maps or Baidu API
- First reverse to GCJ-02, then to WGS84
- Final coordinates are compatible with GPS and international systems
- Cross-reference with known locations to verify accuracy
- This conversion is essential when migrating data from Baidu Maps to international platforms
- The two-step inverse ensures maximum accuracy
- Always check a sample of coordinates for correctness