In Thai astronomy-astrology the first thing that sorts people is not a star sign but the day of the week they were born on. Every day has a ruling planet, and that planet is where the eight Thaksa houses start turning. The arrangement decides your lucky colour, the colour you avoid, your favourable direction, and which Thai consonants may appear in your name. This tool runs those rules and lays the result out on one screen.
Day colours are still everyday life in Thailand — royal ceremonies, hospital uniforms and the candles lit before the Buddha image of each day all come from this table.
Only Wednesday is split in two. After 6 p.m. it becomes the day of Rahu, with its own ruling planet and its own Buddha image.
This tool does not compute planetary longitudes. A full Thai chart needs a sidereal ephemeris and is a separate exercise.
Thaksa assigns eight planets to eight areas of life. The house names are the areas: Bariwan (the people around you), Ayu (lifespan), Det (authority), Si (fortune), Mula (assets), Utsaha (effort), Montri (patrons) and Kalakini (misfortune).
The arrangement is simple. Put Bariwan on the ruling planet of your birth day, then fill the rest clockwise around a fixed wheel. Because the starting point moves with the weekday, the same eight houses sit on different planets for different people.
The wheel is not in planet-number order. It runs Sun, Moon, Mars, Mercury, Saturn, Jupiter, Rahu, Venus — the same order as the numbered Thai consonant groups. Change it and every result changes with it.
Indian astrology arrived in Thailand and fused with an older cult of the weekday. Thai temples line up eight Buddha images, one per day, and people light a candle before their own.
Each day carries a colour: Sunday red, Monday yellow, Tuesday pink, Wednesday green, Thursday orange, Friday light blue, Saturday purple, and Wednesday night grey.
These are social signals rather than preferences. The colour of the reigning monarch's birth day becomes the colour of national occasions, and offices and hospitals still wear day colours.
The lucky colour is the colour of the planet that lands in Si; the forbidden one is the planet in Kalakini. Directions work the same way — the eight Thaksa directions run clockwise starting from the Sun in the north-east.
A Sunday birth puts Venus in Kalakini. Venus is light blue, which produces the well-known rule that Sunday people avoid blue. A Thursday birth puts Saturn there, so black and purple are out.
That derivation is deliberate. Keeping a separate colour table would eventually contradict the wheel; deriving it leaves nothing to contradict.
The 42 Thai consonants and the vowel marks are split into eight groups, one per planet. Each person therefore has a list of letters to keep out of their name: the group belonging to the planet in Kalakini.
The Sun group holds the consonant อ and every vowel mark. The Sun falls into Kalakini for Monday births, which is the origin of the practice of naming Monday children with consonants only and no written vowels.
There are letters to aim for too, from the Si and Montri groups. This is a large part of why changing one's name is common and unremarkable in Thailand.
Rasi are the twelve sidereal signs. Because no precession correction is applied, they begin about 24 days later than the tropical signs most Western readers know, so the two overlap in places and disagree in others.
The animal years match the Chinese twelve but carry Thai names — Chuat the rat, Chalu the ox, Khan the tiger, and so on. The dragon slot is pictured as a naga.
Years are written in the Buddhist era, the Gregorian year plus 543. Thai newspapers, government documents and receipts still use it.
It does not place planets on the ecliptic. A full Thai chart is a square of twelve houses with planets written as numerals, and drawing it needs a sidereal ephemeris. This tool covers the part that closes with a calendar and a rule.
It says nothing about your character or your future. The blurb next to each house describes what that house traditionally governs, which is not a statement about a person.
Some schools turn the wheel anticlockwise for night births. This tool uses the clockwise order that naming practice relies on, and says so rather than offering a toggle that hands the disagreement to the reader.
That is the rule, not a bug. In the Thai tradition the day turns at sunrise, roughly 6 a.m., so a birth at 3 a.m. on Tuesday belongs to Monday. The result says when this correction was applied, and you can switch the rule off to see the calendar day instead.
Eight houses need eight planets, but there are only seven weekdays. Thai astrology counts Rahu, the lunar node, as the eighth planet and gives it Wednesday night. So Wednesday people get an entirely different ruling planet, colour and set of forbidden letters depending on the hour.
It is the colour of whichever planet lands in the Kalakini house. The tool derives it from the arrangement rather than storing a second table, which is why it agrees with the familiar list: Sunday avoids blue, Monday avoids red, Thursday avoids black and purple, Saturday avoids green.
The rule only exists over Thai script. A roman s could be ส, ศ or ษ, and vowel marks belong to a different group again. Guessing the spelling would mean inventing the answer.
The Thai year turns around Songkran in mid-April, not on 1 January. This tool uses 16 April as the boundary, so births from January to early April fall one animal behind the Gregorian year.
What this tool bases its numbers on, and how far those numbers go.
Thai day = weekday after the sunrise (06:00) boundary, with Wednesday 18:00-06:00 assigned to Rahu. Thaksa = Bariwan on the ruling planet, then clockwise around the wheel Sun, Moon, Mars, Mercury, Saturn, Jupiter, Rahu, Venus. Colours, directions and consonant groups follow the planet that lands in each house.Born 4 May 1990 at 09:00 gives Friday, ruled by Venus, with Mars (pink) in Si and Rahu (grey) in Kalakini: lucky pink, avoid grey, and keep ย ร ล ว out of the name.