In the context of Jainism, the terms "Pacham," "Sawansatari," and "Chauth" refer to specific days in the lunar calendar that are significant for rituals, especially during the Paryushan or Daslakshan Parva festivals.

• Pacham means the fifth day of the lunar fortnight (Panchami).
• Chauth means the fourth day of the lunar fortnight (Chaturthi).
• Sawansatari (also spelled Samvatsari) is the most important day of the Jain festival of Paryushan for the Shwetambar sect; it is the day of forgiveness (Kshamavani). For Digambar Jains, Kshamavani is observed on a different day.

Which day is Samvatsari (Sawansatari)?

• For Shwetambar Jains, Samvatsari falls on the Panchami (Pacham) or Chhath (sixth day) of the Shukla Paksha (bright half) of the Bhadrapada month, depending on the local calendar and any leap months (Adhik Maas).
• It is never observed on Chauth (fourth day), but sometimes, due to calendrical adjustments, Samvatsari may shift by a day.

Summary: Samvatsari (Sawansatari) is typically observed on Pacham (fifth day/Panchami) or sometimes Chhath (sixth day), but NOT on Chauth (fourth day).

If you are asking about the correct day for Samvatsari this year or in a specific context, it is recommended to consult the local Jain calendar (Panchang) as sometimes regional variations may apply. But traditionally, Pacham (Panchami) is considered the right day, not Chauth.