BAZI KNOWLEDGE BASE
Solar-term depth in BaZi: elapsed time and monthly qi schedules
Solar-term (one of 24 seasonal markers defined by the Sun’s position along its yearly path) depth describes where a birth falls within its BaZi month: soon after the opening solar term or closer to the next month boundary. It brings seasonal progression within one branch month into the discussion. Elapsed time is a calculation; assigning that position to a hidden stem (an additional element symbol traditionally assigned inside a lower chart symbol) uses a chosen traditional schedule. The two should not be merged into an unexplained precise strength percentage.
Calculate elapsed time before interpreting the qi
Put the birth instant and opening solar-term instant on the same time basis before subtracting. Local clock records depend on the applicable time zone and daylight-saving rule. Do not subtract a zoned birth time from an unspecified local solar-term time.
For a synthetic illustration, suppose the term begins at 10:00 and the birth is at 22:00 the following day, both already on the same time basis. The elapsed interval is 36 hours, or 1.5 twenty-four-hour days. This is neither a real year’s solar-term record nor a personal chart calculation.
How a daily qi schedule differs from an astronomical interval
One Yin-month schedule in Sanming Tonghui assigns five days to Wu, five to Bing and twenty to Jia, a conventional thirty-day outline. Under that schedule, the 1.5-day illustration lies in the first interval. Reproducibility also requires stating what counts as a day and which interval includes a boundary instant.
Actual intervals between month-opening solar terms need not be exactly thirty whole days. The conventional twenty days for Jia still need an explicit boundary treatment when compared with the actual next term. Do not silently scale the schedule to percentages or extend it into the following month.
Disagreement can come from the method itself
The Sanming Tonghui transcription on Shidian Guji first lists daily assignments and then records Zuixingzi’s objection to rigid day divisions, emphasizing progression rather than fixed blocks alone. Different positions are preserved within the same chapter.
When two results differ, compare the qi schedules as well as the time inputs. More decimal places cannot reconcile different interpretive conventions. A daily qi assignment also does not complete a Day Master (the birth-day element used as the chart’s reference) strength assessment by itself.
Si Ling, Si Quan and Si Ming need the author’s definitions
These terms are not three universal independent scores. Si Ling often appears in discussion of acting qi; Si Quan emphasizes which qi holds authority. Whether an author means the month’s principal qi or a daily assignment must be read in context. Combining names from different writers does not create a unified calculation.
Modern writer Cangran Dongze also warns of mixed usage in his discussion of pattern roles and describes Si Ming through an executor analogy. That is an example of his terminology, not a definition shared by every classic. If a stem is called Si Ming, identify it, ask whether it is exposed and clarify its role in that method.
More names do not add more evidence. The month branch (the lower symbol in the birth-month column), actual hidden stems, elapsed position and exposure already let readers follow what an explanation compares. An unexplained Si Ming label should not become a third mysterious score to calculate.
What remains possible with uncertain birth time
If the known birth date is far from a month boundary, the month branch may be clear even when exact elapsed hours are not. Near a solar term or a chosen daily boundary, more than one interval may remain possible. Month uncertainty and within-month uncertainty should be reported separately.
Fine timing is meaningful only with reliable inputs and an explicit rule. It can clarify seasonal progression within a month; it does not turn a few hours’ difference into a ranking of ability, relationships or personal worth.