Nine Star Ki: Finding Your Birth Star, from One White Water to Nine Purple Fire

The nine stars and their natures

The nine stars are One White Water, Two Black Earth, Three Jade Wood, Four Green Wood, Five Yellow Earth, Six White Metal, Seven Red Metal, Eight White Earth, and Nine Purple Fire. Each is assigned an element and a colour.

One White Water flows like water, adapting to any container with flexibility and patience. Two Black Earth receives like the earth itself, a steady, practical star that nurtures things slowly. Three Jade Wood shoots up like a young tree — quick, energetic, expressive. Four Green Wood spreads like the wind, connecting people together with quiet, mediating influence. Five Yellow Earth sits at the very centre of the chart, an imperial star whose influence — for better or worse — is unusually large.

Six White Metal is a heavenly star of responsibility and leadership; Seven Red Metal brings sociability, joy and abundance; Eight White Earth is a mountain star turning change into a firm foundation; and Nine Purple Fire, the star of the Sun and flame, symbolises brilliance, intellect and being noticed.

Working out your Birth Star and Month Star

Your Birth Star is derived from your year of birth using the formula (11 − ((year − 1) mod 9)) mod 9, with a result of 0 read as 9. The key thing to remember is that the Nine Star Ki year begins at the Start of Spring (around February 4th), not January 1st — so anyone born on or before roughly February 3rd is calculated as though born in the previous year.

Your Month Star is derived from the combination of your Birth Star's group and your month of birth. Where the Birth Star reflects your basic, lifelong nature, the Month Star is said to reflect tendencies shaped in early childhood. It is likewise calculated as the previous month if you were born before that month's solar-term boundary.

Yearly, monthly and daily charts, and lucky directions

Nine Star Ki works with "charts" — grids showing how the nine stars are arranged across the eight directions plus the centre. The baseline arrangement places One White in the North, Two Black in the Southwest, Three Jade in the East, Four Green in the Southeast, Five Yellow in the centre, Six White in the Northwest, Seven Red in the West, Eight White in the Northeast, and Nine Purple in the South.

For an actual reading, the star sitting at the centre changes by year, by month, and by day, and every other star shifts direction along with it — producing the yearly, monthly and daily charts. Whichever direction holds a star compatible with your own Birth Star becomes a lucky direction for that period.

However, wherever Five Yellow Earth currently sits is called the Gōō-satsu direction, and its opposite the Anken-satsu direction — both are treated as unlucky no matter how compatible the star would otherwise be. The direction occupied by your own Birth Star (Honmei-satsu) and its opposite (Honmei-teki-satsu) are avoided on the same principle.

How this site calculates it

Your Birth Star is found with the formula above plus the Start-of-Spring correction, and your Month Star is read from the Nine Star Ki month-star table. The daily chart's central star cycles deterministically based on the remainder of elapsed days from a fixed base date, divided by nine.

Lucky directions are calculated by building the day's monthly chart, excluding the Gōō-satsu, Anken-satsu, Honmei-satsu and Honmei-teki-satsu directions, then ranking the remaining directions by how well their star aligns with your Birth Star (through generation or a shared element) — the top three are returned, and the highest-ranked one is shown as your lucky direction.