Diwali is based on the Hindu lunar calendar, specifically the Amanta tradition, which tracks the moon’s phases. The festival celebrates the new moon (Amavasya) of the month of Kartik, which is why the date shifts by about 10–15 days every year relative to our Gregorian calendar.
Think of it like Easter: you know it’s coming, but you can’t mark it on your wall calendar until someone tells you the exact Sunday. The same logic applies here, except Diwali isn’t one day—it’s a five-day blowout, with the main celebration (the Lakshmi Puja) on the third day.
So, when someone asks “When is Diwali?” they usually mean that main day of lights, fireworks, and feasting. In the UK, that day in 2026, for example, fell on October 31st. Spooky coincidence? Maybe. But next year, 2026, it jumps to October 20th—so keep your pumpkins and your diyas on standby.
