Determining whether your Day Master is strong or weak is the first step in BaZi analysis. Use three criteria:
If your Day Master is born in the season when its element is dominant, you have De Ling. Jia Wood born in Yin or Mao month (spring) is strong. Born in Shen month (autumn, Metal season), Wood is weak. The Month Branch carries 40% of the chart's power.
If your Day Master sees its own element or supporting element in the four Earthly Branches, it has roots. Jia Wood sees Yin/Mao (Wood roots) or Hai/Zi (Water nourishing Wood). Two or more roots = De Di.
If other Heavenly Stems show Companion or Seal stars supporting you, you have De Shi. Jia Wood seeing Jia (Friend), Yi (Rob Wealth), Ren (Indirect Seal), or Gui (Direct Seal) means support from peers or mentors.
Two or three factors = strong. One = balanced. None = weak. The Month Branch weighs heaviest — born in season is basically strong, born out of season is basically weak. Fine-tune with roots and stem support.