How Da Yun starting age is calculated

Choose the solar-term target from sequence direction

The starting-age calculation begins with the resolved birth instant and the Luck Pillar direction. Under MingWeave’s rule, the forward sequence measures toward the next relevant Jie solar term, while the reverse sequence measures back toward the previous relevant Jie. The exact target name and timestamp appear in the calculation trace.

This target choice is distinct from Li Chun’s role as the Year Pillar boundary. It also uses Jie terms rather than an arbitrary calendar month edge. If a product measures to another term or rounds the term to a date, its starting age can differ even when its pillar sequence agrees.

Convert elapsed time with a declared ratio

MingWeave uses the conventional ratio of three days of elapsed time to one year of starting age. One day corresponds to four months, and two hours correspond to roughly ten days in the derived age interval. The engine performs the conversion from the exact duration rather than manually counting printed calendar dates.

Suppose a synthetic forward calculation finds 18 days between birth and the target Jie. Dividing by three produces a starting age of six years before the documented rounding and calendar projection rules are applied. The example demonstrates the ratio only; a real result uses precise instants and versioned data.

Rounding and age labels must be visible

A duration rarely converts to a whole number of years. MingWeave retains a structured years-months-days representation and computes an approximate Gregorian start date using its documented calendar rules. It labels age on an elapsed-age basis so a reader does not confuse it with traditional nominal-age counting.

Other systems may round to months, start counting at age one, or present only an integer. Those displays can look contradictory while sharing a similar underlying interval. Compare the raw duration, ratio, rounding, age basis, and start-date projection before deciding that the calculation differs.

Unknown time and near-term births require restraint

When the birth time is unknown, the calendar date alone defines a range of possible instants. That range creates a corresponding start-age interval. MingWeave marks the limitation and avoids implying minute-level precision. A birth close to the target Jie can be especially sensitive to even a modest clock uncertainty.

Use the starting age as a transparent output of the selected cultural method, not a guaranteed onset of life events. Preserve the direction, target term, time-distance trace, Method Profile, engine version, and data version when comparing charts. The method is only reproducible when those conditions travel with the number.

• Direction selects previous or next Jie.
• Exact elapsed time is converted at three days per year.
• Rounding and age basis are part of the result.