陰陽道ラボ — 暦を計算して確かめる

Field notes

The calculation engine derives 二十四節気 from the Sun’s apparent longitude and numerically solves for the moment each threshold is reached, rather than importing calendar data. The site says these results were checked against known solar-term dates within five minutes, while its 九星配置 and directional judgments were compared with multiple other 気学 sites. A stated limitation is that favorable and unfavorable interpretations differ among schools.