There is no fixed “conversion” between swādhyāy and upvās in Jain scriptures.

• Upvās (fasting for a day) is one of the six external austerities (bahya tapa).
• Swādhyāy (study of scriptures) is one of the six internal austerities (antara tapa).
• The punya (merit) depends on the purity of intention (bhāva), right faith, careful conduct, and how correctly each practice is done—not on a set number.

Some community sayings compare numbers to motivate practice, but such exact equivalences are not given in canonical texts. Both are highly praised; do whichever you undertake with samyak bhāva and discipline.