In Jainism, fasting (upvas) and other forms of penance (tapas) are ways to purify the soul and reduce karmic bondage. However, there is no canonical rule that "one upvas equals a fixed number of hell years." The karma that binds a soul and determines its future experiences in hell or in this world is complex and depends on the balance of many actions over many lifetimes, including intention, nonviolence, truthfulness, and restraint.

Key points to keep in mind:

• Fasting can help reduce the accumulation of negative karmas and can also help burn up certain past karmas, especially if done with proper spirit (non-violence, sincerity, and self-control).
• The result of karmic balance is not a simple one-to-one mapping like “one upvas equals X years in hell.” Different karmas have different intensities, types, and durations, and their effects play out across innumerable lifetimes.
• There are differences in interpretation between Digambar and Shwetambar traditions about specific practices and their spiritual outcomes. In any case, the emphasis is on purification and restraint rather than on numerical reckonings.

If you’d like, I can explain how fasting is described in Jain scriptures (general principles of pratikrama, samayik, etc.) and how it fits into the broader karmic framework, or provide guidance on how to observe a meaningful upvas today.