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Tong Shu Calendar Reference

Auspicious Business Opening Dates for August 2026開業 · August 2026

By Master Sean Chan · Updated

This month carries Li Qiu (立秋) — start of the BaZi autumn on August 7 (Singapore time): the BaZi calendar's sectional boundary for the month. Autumn proper begins with this term; Wood-day rankings tend to weaken from this point.Below is the universal Chinese metaphysics ranking of every day in August 2026 for opening a business (開市), derived from the classical Tong Shu (通書). Opening is treated as a 'beginning' — the rules favour 開 (Opening) and 建 (Establishing) officers and Yellow Dao days carrying 天德 / 月德 protection.

Top-ranked dates this month

31
days in August
25
pass hard requirements
5
rank as 上吉
5
top picks below
DateDay PillarOfficer 建除 Mansion 宿Clash 沖Class
12026-08-13壬戌滿 Filling箕辰 (Dragon)上吉
22026-08-19戊辰成 Completing室戌 (Dog)上吉
32026-08-28丁丑執 Holding井未 (Goat)上吉
42026-08-05甲寅危 Dangerous翼申 (Monkey)上吉
52026-08-09戊午開 Opening氐子 (Rat)上吉

All days in August 2026

DateDay PillarOfficerMansion ClashNotable factorsClass
2026-08-01庚戌平鬼辰 Dragon建除 平 · 黃道平
2026-08-02辛亥定柳巳 Snake黃道吉
2026-08-03壬子執星午 HorseFailed requirement: not_year_break大凶
2026-08-04癸丑破張未 GoatFailed requirement: not_month_break大凶
2026-08-05甲寅危翼申 Monkey天德 · 月德 · 建除 危上吉
2026-08-06乙卯成軫酉 Rooster四絕 · 建除 成 · 宿 軫平
2026-08-07丙辰成角戌 Dog建除 成 · 黃道吉
2026-08-08丁巳收亢亥 Pig月德合 · 宿 亢 · 黃道吉
2026-08-09戊午開氐子 Rat天德合 · 建除 開 · 宿 氐上吉
2026-08-10己未閉房丑 Ox建除 閉 · 黃道凶
2026-08-11庚申建心寅 Tiger—平
2026-08-12辛酉除尾卯 Rabbit—平
2026-08-13壬戌滿箕辰 Dragon月德 · 建除 滿 · 宿 箕上吉
2026-08-14癸亥平斗巳 Snake天德 · 建除 平 · 宿 斗吉
2026-08-15甲子定牛午 HorseFailed requirement: not_year_break大凶
2026-08-16乙丑執女未 Goat建除 執 · 黃道吉
2026-08-17丙寅破虛申 MonkeyFailed requirement: not_month_break大凶
2026-08-18丁卯危危酉 Rooster月德合 · 建除 危 · 宿 危平
2026-08-19戊辰成室戌 Dog天德合 · 建除 成 · 黃道上吉
2026-08-20己巳收壁亥 Pig黃道吉
2026-08-21庚午開奎子 Rat建除 開吉
2026-08-22辛未閉婁丑 Ox建除 閉 · 黃道凶
2026-08-23壬申建胃寅 Tiger月德吉
2026-08-24癸酉除昴卯 Rabbit天德吉
2026-08-25甲戌滿畢辰 Dragon建除 滿 · 黃道吉
2026-08-26乙亥平觜巳 Snake建除 平平
2026-08-27丙子定參午 HorseFailed requirement: not_year_break大凶
2026-08-28丁丑執井未 Goat月德合 · 建除 執 · 宿 井上吉
2026-08-29戊寅破鬼申 MonkeyFailed requirement: not_month_break大凶
2026-08-30己卯危柳酉 Rooster建除 危平
2026-08-31庚辰成星戌 Dog建除 成 · 黃道吉
Personalised next step

BaZi-Aligned Date Report — August 2026

USD 388

A personalised PDF that re-ranks every business opening-suitable day in August 2026 against your BaZi (and, for weddings/ROM, your partner’s BaZi). It surfaces:

Order the report →

See the full glossary of classical date-selection terms in the BaZi Glossary & Auxiliary Stars.

Further reading from the blog

Selected posts from Master Sean Chan's blog covering this topic and closely related ones in practice:

Frequently asked

Why isn’t my day on the list of top 5?

The top list is the universal ranking before any personal adjustment. Many couples find their best date isn’t in the top 5. Once you account for your day pillars, the right day often shifts. That’s exactly the gap the BaZi-Aligned Date Report fills.

What does 大凶 mean and can it ever be overridden?

大凶 means the day fails a hard classical requirement: 月破 (month break), 歲破 (year break), or 四離/四絕 (a quarter-day boundary). These cannot be overridden by personal alignment; they are excluded categorically. Choose another day.

Why don’t you show times here?

Hour selection is personal. The right hour depends on your day pillar and the chosen day’s element relationship to it. Publishing universal “auspicious hours” misleads readers into thinking a generic hour is safe; it isn’t. Hours are included in the personalised report.

Where do these scores come from?

The classical Tong Shu (通書) tradition: 建除十二神 (Twelve Officers), 二十八宿 (Twenty-Eight Mansions), 月德 / 天德 (monthly and yearly virtue stars), 黃黑道 (Yellow/Black Dao), and the Dong Gong (董公) per-purpose rules. We compute these directly from astronomical solar terms — no app shortcuts.

Should I open the business on the same day as my company registration?

If you can — yes. Aligning the opening with the legal incorporation compounds the day’s influence on both events. If they have to be different, prioritise the opening (the customer-facing first day) over the registration date.

Methodology

Each day’s pillar is computed from the 60 Jiazi rotation anchored against the published Tong Shu, not from any single calendar app. The BaZi year flips at Li Chun (立春) and the BaZi month flips at every sectional solar term, both calculated from VSOP87 solar-longitude data so the boundaries land on the right minute. Twelve Officers and the 28 Mansions each rotate deterministically against well-known anchors.

The per-purpose weights are Dong Gong’s (董公擇日) — adjusted where modern almanacs disagree, in favour of the Hong Kong Observatory and Taiwan CWB lineage. Auspicious stars add to the score, taboo stars subtract, the day’s officer and mansion shift it further, and Yellow Dao adds a final small bonus. The final number gets capped at 100 and mapped to one of five tiers.