What is the exact phase of the moon on the day of Diwali?

The exact phase of the Moon on the main day of Diwali is Amavasya, the new-moon day.

In the Hindu lunisolar calendar, Amavasya marks the conjunction of the Sun and Moon, when the Moon is generally not visible from Earth. Diwali is observed on Kartika Amavasya, although calendar conventions and regional observances can affect the civil date.

Diwali is often described as a five-day festival rather than a single date. Dhanteras begins the sequence, followed by Naraka Chaturdashi, the main Diwali night, Govardhan Puja or Annakut, and Bhai Dooj in many traditions. The neighbouring full-moon term, Purnima, is therefore a common mix-up, but it is the opposite lunar phase.

Amavasya also has wider religious importance in Hindu practice. It is associated with ancestor rites, offerings, fasting, and other observances, so Diwali’s moonless night carries both calendrical and symbolic significance: lamps are lit during the darkest night of the lunar cycle.