According to Wikipedia, PUBG: Battlegrounds maps range up to 64 square kilometers.
That maximum corresponds to the large 8-by-8-kilometer map format used by maps such as Erangel and Miramar. Multiplying the two dimensions gives 64 square kilometers, although the usable land area can be smaller because maps include water, coastlines, and inaccessible terrain.
PUBG’s map design depends heavily on scale. Large maps give squads more room to loot, rotate, drive, and choose strategic positions before the shrinking blue zone forces encounters. Smaller maps compress those decisions and usually produce faster, more frequent firefights.
The figure is a map-dimension description, not the area of the final safe zone. During a match, the playable circle repeatedly contracts toward a random location. Players therefore begin across a broad battlefield but finish in a much smaller combat area.