In Jain cosmology, Jambudweep (Jambudvipa) is the central continent of Bharata (the earthly world) and is described as a very vast land around Mount Meru. The Jain texts discuss its structure in symbolic, cosmological terms rather than giving a single fixed earthly measurement. Because different Digambar and Śvetāmbara sources vary in their details, there isn’t one universally agreed “size” for Jambudweep. The emphasis is on its central position, the presence of many cities and kingdoms, and the moral/spiritual significance of the land, rather than a precise numerical area.

If you’d like, I can point to specific Jain passages or sutras that describe Jambudweep in more detail (and note where Digambara and Śvetāmbara traditions differ).