In Jainism, Aayambil (or Aambil) and Upvaas (Upvas) are two different types of austerities (fasts), each with its own significance and rules:

• Upvaas (Upvas): This is a complete fast, typically observed by not consuming any food or water (sometimes only boiled water) from sunrise to the next sunrise (or sunset to sunset).
• Aayambil (Aambil): This is a special type of food restriction where, for the entire day, one eats only once, and the food is very plain—boiled, without salt, oil, ghee, milk, curd, green vegetables, or fruits.

On the day of Chaumasi Chaudas (the four-monthly observance), both Upvas and Aayambil are considered significant forms of penance.

Equivalence:

• There is no strict scriptural equivalence mentioned in Jain Agamas or traditional texts that says "1 Aayambil = X Upvas" or vice versa.
• However, in practice and for certain rituals (like “Shubh Labh” during Chaumasi Chaudas), sometimes laypersons (Shravaks) ask this question. Generally:

- Upvas is considered a stricter and more difficult penance than Aayambil. - If for health or other reasons someone cannot do Upvas on Chaumasi Chaudas, doing Aayambil is suggested as a milder alternative. - In community practice, 1 Upvas is considered more meritorious than 1 Aayambil, but no fixed numerical equivalence is prescribed in Jain scriptures.

Summary (as per Jainism):

• There is no scriptural conversion: 1 Aayambil is not directly equal to any number of Upvas.
• If unable to do Upvas, performing Aayambil is allowed and considered auspicious.
• The merit (Punya) of Upvas is generally greater than Aayambil, but both are valuable austerities.

References:

• Jain Agamas and commentaries (for definitions of Upvas and Aayambil)
• "Jain Dharma ka Maulik Swaroop" by Pandit Dalsukhbhai Malvaniya
• "Jain Vrat aur Tap" by Acharya Mahaprajna

If you need more details about the procedures or significance of these fasts, please let me know!