How NPCC Calculates: Our Methodology & Sources
NPCC turns your birth details into charts across five systems. This page explains which school each system follows, the calculation rules we apply, and the classical texts our readings and Learn articles are based on.
What birth details do you need?
- Your date, time and place of birth. You enter ordinary local clock time; NPCC converts it to true solar time using the longitude of your birthplace.
- If the birth hour is unknown, the hour pillar (and anything depending on it) is left out rather than guessed. The Birth Hour Finder can help estimate it.
BaZi (Four Pillars of Destiny)
- School: Zi Ping (子平) method, reading the chart from the Day Master, its strength, structure (格局), the Ten Gods and climate balance (調候).
- Year starts at Li Chun (立春), not 1 January or Lunar New Year. Months change on the 12 solar terms (節), not lunar months.
- True solar time is used. The day changes at 23:00 (the start of the Zi hour 子時), following the pillar calendar.
- Classical sources: Zi Ping Zhen Quan 《子平真詮》, Di Tian Sui 《滴天髓》, Qiong Tong Bao Jian 《窮通寶鑑》 and San Ming Tong Hui 《三命通會》.
Zi Wei Dou Shu (Purple Star Astrology)
- School: San He (三合派) palace-and-star method, with the Si Hua (四化) transformations from the year stem.
- Star placement follows the traditional rules recorded in Zi Wei Dou Shu Quan Shu 《紫微斗數全書》, computed with the open-source iztro engine.
- Uses the lunar date and the two-hour period of birth (時辰), based on true solar time; the day changes at 23:00.
Qimen Dun Jia
- School: rotating-plate (轉盤) time Qimen, the most widely used modern form.
- Rules follow the classical Yan Bo Diao Sou Ge 《煙波釣叟歌》 and Qi Men Dun Jia Tong Zong 《奇門遁甲統宗》 traditions.
- Charts are cast from the solar term and the hour pillar, using true solar time.
Western Astrology
- Tropical zodiac, with planet positions from a high-precision astronomical ephemeris (astronomy-engine).
- Uses your clock time and birthplace converted to UTC. The day changes at midnight, as in the civil calendar.
Numerology
- Pythagorean system. Your Life Path Number is the digit-sum of your full birth date, keeping master numbers 11, 22 and 33.
Who is behind NPCC?
- NPCC is built by ULT Studio Limited. Calculations are designed and checked by the NPCC Research Team against the sources above.
- Learn articles are written in the voice of The Little Slime Scribe, our friendly guide persona, and every classical quote names its source book.
What NPCC is (and is not)
- Readings describe tendencies drawn from traditional systems, for reflection and entertainment.
- They are not medical, legal or financial advice. See our Disclaimer for details.