In Jain cosmology, the yojana is a traditional distance unit used in many Kalpas and cosmological descriptions. The exact length assigned to one yojana varies a bit among authorities, but the most common convention used by many Jain scholars places 1 yojana at about 8 miles (roughly 13 kilometers).

Notes:

• Some texts and commentaries may give slightly different values (e.g., ranging a bit above or below 13 km), but 8 miles is the standard commonly cited in Jain discussions.
• Distances in Jain works are often used to describe the scale of mountains, continents, and the cosmic diagram rather than practical surveying, so the key idea is the relative vastness rather than a single fixed measurement.

If you’d like, I can summarize how yojana is used in a particular Jain text or tradition (Digambar vs. Shwetambar) and give exact verse references.