Diwali's main night coincides with which lunar phase?

Diwali’s main night coincides with Amavasya, the new-moon phase in the Hindu lunisolar calendar.

Amavasya is the night when the Moon is not visibly illuminated from Earth because it lies approximately between Earth and the Sun. Diwali is observed during this darkest point of the lunar month, which helps explain the festival’s famous abundance of lamps, candles, and other lights.

The central night is commonly associated with Lakshmi Puja, when devotees welcome Lakshmi, the goddess of wealth and prosperity, into clean and illuminated homes. Families light diyas near entrances and windows, create rangoli designs, exchange sweets, and may set off fireworks, though local rules vary.

Amavasya is sometimes confused with Purnima, the full-moon phase, or with Pratipada and Ekadashi, which are lunar days rather than the name of the new-moon phase. Regional Hindu calendars can differ in how they label the surrounding lunar month, but the festival’s central astronomical phase remains the new moon.