Over the years working with Classical Feng Shui, I’ve noticed the same thing happens every time someone mentions their Kua number: the eyes glaze over. “Isn’t that something the calculator just tells me?” And sure — it can. But here’s the thing I’ve learned from untangling dozens of homes: the people who actually use their Kua number well are the ones who understand where it comes from.
So let’s fix that today. In about three minutes you’ll be able to work out your Kua (or Gua) number by hand — no apps, no tables, just your birth date and a couple of rules. Why bother? Because once you see it, you stop treating this as a mysterious number and start reading it as the eight-mansions map of your own energy. Let me show you.
Classical Feng Shui doesn’t run on the calendar most of us use. The energetic year turns on Li Chun, the Start of Spring, which usually lands around February 4th. If you were born in January or early February, your “Feng Shui year” might actually be the previous year.
Example: someone born on 25 January is still, energetically, in the previous year for Kua purposes. Get this wrong and you’ll carry the wrong life gua your whole life. So step zero is: know your true solar birth year.
With that sorted, here’s the whole method.
Take the last two digits of your (solar) birth year and add them together. If you get a two-digit number, add those digits again until you land on a single digit from 1 to 9.
Let’s run it for a person born in 1991: 9 + 1 = 10 → 1 + 0 = 1. That single digit is the key you’ll plug into the next rule.
This is where it splits, and the rule changed for people born in 2000 or later — a detail that trips up a lot of online guides.
Example (1985): 8 + 5 = 13 → 1 + 3 = 4 → 10 − 4 = 6. Kua 6.
Example (1991): 9 + 1 = 10 → 1 + 0 = 1 → 1 + 5 = 6. Kua 6.
There’s one exception in the eight-mansions system: the number 5 has no direction, because it sits in the center of the Lo Shu square. So when a calculation lands you on 5, you swap it:
A woman born in 1990 calculates: 9 + 0 = 9 → 9 + 5 = 14 → 1 + 4 = 5 → swap to 8.
That’s genuinely the whole trick. Three steps, one exception, done.
Once you have your number, it drops you into one of two groups — East Group (Kua 1, 3, 4, 9) or West Group (Kua 2, 6, 7, 8) — and each group points to four lucky and four unlucky directions. The two most useful ones to start with:
In practice I usually tell clients not to chase all eight directions at once. Start with your Sheng Qi and Tian Yi, get those two placements right at your front door, your bed, and your desk, and you’ve already covered most of the benefit. If you ever wonder which of the two matters more — wealth or health — there’s a whole breakdown of that exact question in Sheng Qi vs Tian Yi: which good direction to prioritize for wealth.
For a fuller framework, it’s worth seeing how your Kua direction slots into the wider Ba Zhai (Eight Mansions) system — and how it pairs with the other system in the same school, described in the Sheng Qi and Tian Yi guides.
Hand calculation is great for understanding, but it has two weak spots: the Li Chun solar-year boundary, and simple arithmetic slips under pressure. For a golden birthday — a child, an anniversary, your own date — I’d never rely on memory alone.
So here’s what I do on the job: I calculate by hand the old way (it keeps the system alive in your head), then I confirm the result with our Free Kua Number Calculator, which uses professional astronomical data to handle the exact Li Chun shift for January and February birthdays. Thirty seconds, no guesswork.
If you’d like the deeper interpretation once you know your number, the Kua Numbers pages break down each of the eight gua — its element, lucky colors, and best directions — so you can take your number and actually put it to work room by room.
