Answer

A tithi does not change at a fixed clock time. It changes at the exact astronomical moment when one lunar day ends and the next begins. That time can be any time of day or night.

Explanation

In Jain tradition, tithi is calculated from the lunar calendar, so its ending time varies daily and by location. For practical observance, people usually refer to the local Jain panchang, which shows:

• the start time of the tithi
• the end time of the tithi
• which tithi is present at sunrise

Spiritual Understanding

For Jain observances, the important thing is not a fixed clock time, but the correct tithi according to the panchang. This helps preserve discipline and accuracy in fasting, festivals, and religious vows.

Takeaway

There is no universal time when tithi changes. It changes according to the lunar calculation, so always check the local Jain panchang for the exact timing.