How to Calculate Your BaZi Chart: Step-by-Step Guide

Aug 14, 2026 · 6 min read · bazi calculator guide

A BaZi chart is calculated from your birth date and time: the year, month, day and hour are each converted into one Heavenly Stem and one Earthly Branch, giving 8 characters in 4 pillars. The calculation itself is pure astronomy — a fixed mapping from the solar calendar to the Chinese sexagenary cycle — so any two correct calculators produce the same chart. Here's exactly how it works, step by step.

In this guide you'll learn what information you need, how each of the four pillars is derived, why the Chinese solar terms (节气) matter more than the lunar calendar, and how to read your finished chart.

What You Need to Calculate a BaZi Chart

Three pieces of information:

1. Birth date — year, month and day (solar calendar / Gregorian calendar; BaZi is not calculated from the lunar calendar date)
2. Birth time — the more precise the better, because the Hour Pillar changes every 2 hours
3. Birth location (optional, for professionals) — used to correct for true solar time; for general reading, standard time is acceptable

If you don't know your birth time, you can still calculate 6 of the 8 characters — only the Hour Pillar is affected.

Step 1: Split Your Birth Time into a Chinese "Hour" (时辰)

Traditional Chinese timekeeping divides the day into 12 double-hours (时辰), each covering 2 modern hours:

The Zi hour starts at 23:00, not midnight — so someone born at 23:30 on June 15 already belongs to the next day's Hour Pillar in the traditional system. Most calculators (including ours) follow this convention.

Step 2: Find the Year Pillar (年柱)

The Year Pillar is not your lunar new year sign. BaZi years begin at Li Chun (立春, "Beginning of Spring"), which falls around February 3–5 each year on the solar calendar. Anyone born between January 1 and Li Chun still belongs to the previous BaZi year — even if they already celebrated Chinese New Year in the same period. This is the single most common mistake in BaZi calculation.

Your Year Pillar = the sexagenary pair (stem + branch) assigned to your BaZi year.

Step 3: Find the Month Pillar (月柱)

The Month Pillar is determined by the 24 solar terms (节气), not by the lunar months. Each BaZi month begins at a solar term boundary (节), roughly every 30 days:

• The year has 12 BaZi months, each starting at one of the 12 "section" terms (立春, 惊蛰, 清明, 立夏, 芒种, 小暑, 立秋, 白露, 寒露, 立冬, 大雪, 小寒)
• Born before the term boundary → you belong to the previous BaZi month
• Born on or after the term boundary → the new month

For example, a March 5 birth may still be in the Tiger month (寅月) if it falls before 惊蛰, or in the Rabbit month (卯月) if after.

Step 4: Find the Day Pillar (日柱)

The Day Pillar is the foundation of the entire chart. It cycles through the 60 sexagenary combinations — 10 Heavenly Stems × 12 Earthly Branches = 60 unique pairs, no repeats until day 61. The cycle has run continuously since antiquity, and the Day Pillar is the most precisely determined of the four pillars (it changes exactly at midnight).

The Heavenly Stem of the Day Pillar is your Day Master (日主) — the single most important character in your chart, representing you.

Step 5: Find the Hour Pillar (时柱)

The Hour Pillar combines the 12 double-hours (Step 1) with the day's stem, using the traditional hour-stem sequence. The earthly branch is fixed by the time; the heavenly stem is derived from the Day Pillar's stem. That's why the Hour Pillar can only be calculated after the Day Pillar is known — and why an accurate birth time matters.

Step 6: Read the Result

Once you have all four pillars, you can derive everything else:

• Five Elements balance — each of the 8 characters carries one of the Five Elements (Wood, Fire, Earth, Metal, Water); counting them shows which elements dominate and which are missing
• Ten Gods (十神) — each character's relationship to your Day Master (wealth, authority, peers, output, resources)
• Hidden Stems (藏干) — each Earthly Branch contains one to three hidden stems that add depth
• Na Yin (纳音) — the classical "sound" of each pillar, like "Sword of Metal" or "Water Under Willow"

Most people don't calculate by hand — the conversion tables cover thousands of years. A good calculator (like our free BaZi calculator) does all six steps in under a second, in your browser, with no data leaving your device.

Manual vs Calculator: Which Is Right?

Calculating by hand teaches you the logic, but it requires the full solar-term calendar plus a 60-cycle conversion table — roughly 15–30 minutes per chart and easy to get wrong. Calculators apply the same rules instantly and consistently. For learning, trace one chart by hand using the steps above; for anything practical, use a calculator — the result will be identical if both follow the solar-term convention.

Frequently Asked Questions

What information do I need to calculate my BaZi chart?

Your birth date and time on the solar (Gregorian) calendar, plus optionally your birth location for true solar time correction. The year, month, day and hour are each converted into one Heavenly Stem and one Earthly Branch, producing 8 characters in 4 pillars.

Does BaZi calculation use the lunar calendar?

No. BaZi is calculated from the solar calendar with Chinese solar terms (节气) as month boundaries. The Year Pillar begins at Li Chun (立春, around February 3–5), not at lunar Chinese New Year. This is the most common mistake in BaZi calculation.

How many Heavenly Stems and Earthly Branches are there?

There are 10 Heavenly Stems (甲 to 癸) and 12 Earthly Branches (子 to 亥). Combined in the sexagenary cycle they produce 60 unique pairs, which cycle continuously and never repeat until day 61.

What if I don't know my birth time?

You can still calculate 6 of the 8 characters. Only the Hour Pillar requires the birth time; the Year, Month and Day Pillars are unaffected. The Hour Pillar is simply marked as unknown, and the reading covers the rest of the chart.

When does the BaZi year begin?

The BaZi year begins at Li Chun (立春, "Beginning of Spring"), which falls around February 3–5 on the solar calendar each year — not at lunar Chinese New Year (which moves between January 21 and February 20). The zodiac sign follows the lunar new year, but the BaZi Year Pillar follows Li Chun.

Is calculating a BaZi chart free?

Yes. The calculation is a fixed astronomical conversion, and many accurate free calculators exist online. Our free BaZi calculator runs entirely in your browser — no signup, no data sent to any server.

Now you know how BaZi is calculated — see your own chart in seconds. Use the free BaZi calculator to get your four pillars, Day Master and Five Elements balance, then get a complete personalized reading that explains what your chart means for your career, relationships and growth — 8–15 pages, delivered within 24 hours.