Panchang · 6 min read
Why a tithi rarely matches a calendar day
A lunar day is measured by the Moon’s distance from the Sun — not by midnight. Here is how to read one, and why your festival may begin in the afternoon.
What a tithi measures
Each month the Moon laps the Sun once. Divide that lap — 360 degrees of separation — into thirty equal arcs of 12°, and each arc is a tithi. The first fifteen belong to the waxing fortnight, Shukla paksha; the next fifteen to the waning Krishna paksha.
Because the Moon’s speed changes along its orbit, a tithi can last anywhere from roughly nineteen to twenty-six hours. It almost never lines up with a sunrise-to-sunrise day.
Why your festival may start in the afternoon
Traditional practice usually names a day by the tithi in force at sunrise — the udaya tithi. Observances tied to a specific tithi, though, follow the tithi itself, so a vrat can begin or end partway through the day.
The calendar on your wall counts days. The Panchang counts the Moon.
Skipped and repeated tithis
When a short tithi begins after one sunrise and ends before the next, no sunrise falls inside it: the tithi is “skipped” in day names (kshaya). When a long tithi spans two sunrises, it names two days (adhika).
How to read our Panchang
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