The concept of the Void comes from the logic of the Sexagenary Cycle. The ancients matched the Ten Heavenly Stems with the Twelve Earthly Branches; the least common multiple of ten and twelve is sixty, forming sixty Stem-Branch pairs grouped into ten pairs per xun. Since there are two more Earthly Branches than Stems, each xun inevitably has two Branches without a corresponding Stem—these are the Void of that xun. For example, in the Jiazi xun (pairs from Jiazi to Guiyou), the leftover Branches Xu and Hai become the Void. In practice, a Bazi practitioner usually takes the Day Pillar (Ri Zhu) as the reference, identifies its xun, finds the corresponding Void Branches, and checks whether any of the four pillars (year, month, day, hour) have a Branch falling into this Void. Understanding this mechanism helps us appreciate how the ancients used the mathematical relationship between Stems and Branches to build a symbolic system—rather than mystifying it.

Traditional interpretations of the Void in Bazi are quite diverse. Overall, the Void symbolizes a quality of "emptiness, vacancy, and elusiveness." When an Earthly Branch falls into the Void, the life aspects represented by that pillar—such as the Year Pillar for ancestors and early years, Month Pillar for parents and career, Day Pillar for self and spouse, and Hour Pillar for later years and children—may appear more fluctuating or less defined in a practitioner's reading. Additionally, the Void is often interpreted alongside the Ten Gods (Shi Shen). For instance, if the Wealth God lands in the Void, it might be seen as a light attitude toward money or money flowing in and out; if the Seal God is in the Void, it may relate to ups and downs in academics or documentation. It's important to note that these are traditional symbolic interpretations, not fixed destiny verdicts. The Void also has modifying conditions—such as "resolved when encountering clashing or combining"—so it is not entirely negative.

When it comes to the Void, the most important thing is to maintain a rational and balanced mindset. Ancient Bazi texts hold inconsistent views on the Void: some schools consider it a sign of depletion, while others believe that "a malicious star falling into the Void can actually neutralize its harm," showing that this concept has great interpretive flexibility. In other words, a solitary Void cannot determine one's fortune or misfortune—it must be analyzed together with the overall natal chart configuration, the strengths and weaknesses of the Wu Xing (Five Elements), and the Major Luck Cycles (Da Yun) and Annual Luck (Liu Nian). Treating the Void as a cultural symbol and a tool for self-awareness may be more meaningful than fixating on luck-judging. It reminds us that certain areas of life require more grounded effort, and that what truly shapes our lives are our choices, efforts, and mindset—not any single term on the natal chart.