The ChatGPT Saju Prompt, and the Step Everyone Skips

The saju prompt going around TikTok works, with one gap: it hands ChatGPT your birthday and expects the model to work out your four pillars on its own. Compute the eight characters first, paste them into the prompt, and the same request turns into an interpretation of your chart instead of a chart the model invented.

Here is the prompt in full, what it does well, the step it leaves out, and the version to use instead.

The prompt that is going around

The version that spread in spring 2026 came from a Korean-American food creator with about 1.5 million TikTok followers, replying to a comment asking how she had done hers. Written out, it is one request plus three facts:

Can you give me a full and detailed Four Pillars (saju) reading, including personality analysis, ideal careers, relationship tendencies, health insights, and decade-based luck flow? My birthday is MM/DD/YR, I was born at 12:00 AM/PM, and I am female/male. Please use the Solar Calendar.

That is the circulating text almost word for word. We name the system saju rather than by the English book title it usually travels under, and the rest is unchanged.

It is a better prompt than it looks. Four things in it are doing real work:

• It names the sections. Personality, career, relationships, health, and decade-based luck flow are the standard chapters of a Korean reading, so the model answers in the right shape instead of improvising a format.
• It asks for detail. Without that word, most models return five short paragraphs and stop.
• It supplies a birth time. The hour pillar is two of the eight characters, and a reading without it is missing a quarter of the chart.
• "Please use the Solar Calendar" is the sharpest line in it. Korean families often record a birthday on the lunar calendar, and saju is computed from the solar date. That one sentence prevents a whole class of wrong answers.

The step it skips

Everything the prompt supplies is about you. Nothing in it is about your chart. So before the model can write a single sentence of interpretation, it has to do a second, completely different job: turn a date, a time, and a gender into eight characters.

Those are not the same skill. One is language. The other is calendar arithmetic with three traps in it:

A concrete pair, computed with our own engine. Two births in Seoul, one hour apart, on the same calendar day:

Ipchun 2026 falls at 05:02 Seoul time on February 4. One of those births is 40 minutes before it, the other 20 minutes after. Same date, same city, and two of the four pillars are different, including the year pillar that sets the tone of the whole read. A model answering from memory has to know that instant to the minute to get this right, and it cannot show you the number it used.

We tested exactly this. The mechanism, the boundary cases, and a measured comparison against GPT live in why ChatGPT gets your saju wrong.

The prompt to use instead

Fix the chart first, then let the model do the part it is genuinely good at. This is the prompt our calculator hands you, with your own pillars already filled in:

Please give me a detailed Four Pillars (Saju) reading. Do NOT recalculate the chart; use exactly these pillars, which were computed with a real manseryeok calendar (solar terms + birth-time correction): Year 乙巳 (EUL SA), Month 己丑 (GI CHUK), Day 己酉 (GI YU) (day master Earth · Yin), Hour 丙寅 (BYEONG IN). Cover personality, relationships, career, and the current 10-year luck pillar. Chart computed by koreansaju.xyz.

Three differences from the viral version, and each one matters:

1. It supplies the eight characters. The model now has nothing to guess.
2. "Do NOT recalculate" is not decoration. Without it, models routinely "check" the pillars you gave them, decide they look off, and quietly substitute their own.
3. It gives the day master explicitly. The day stem is the reference point every other character is read against, so naming it keeps the interpretation anchored.

Getting your pillars in a few seconds

Our ChatGPT saju prompt page does the calendar half: enter your birth date, time, and city, and it computes the four pillars from solar-term boundaries and solar time at your birth longitude, then gives you the prompt above with your characters already in it. One copy, one paste. No signup, and the chart is free.

If you would rather see the whole chart first, the free saju calculator shows the same pillars plus your five-element balance and your day pillar card.

Follow-ups worth asking

Once the model is working from a fixed chart, the conversation is where the value is. These tend to produce something better than the first answer:

• "Which element is my chart short on, and what does that tend to look like day to day?"
• "Read my day master against my month branch specifically. What tension is in that pair?"
• "You said I tend to withdraw under pressure. Which characters in the chart are you reading that from?"
• "Keep the same pillars and describe this as tendencies rather than conclusions."

That last one is worth repeating whenever the tone drifts. Saju describes patterns you can work with, not outcomes that are already settled, and a model will match whichever register you ask for.

If you do not know your birth time

Say so, and say it plainly: "birth time unknown, do not guess the hour pillar." The year, month, and day pillars carry most of a chart, and the day master still sits in the day pillar. What you lose is the hour pillar's nuance. What you avoid is worse: a guessed noon or midnight silently sets two characters, and midnight is the single worst guess because it sits right on the 23:00 day boundary.

Our calculator handles this the same way. Leave the time blank and it marks the hour pillar unknown and labels the chart approximate rather than filling in a number.

The short version

The viral prompt asks the right questions. It just asks the wrong thing to do the arithmetic. Compute the pillars with a calendar, paste them in, tell the model not to recalculate, and the rest of that prompt finally has something true to work with.

For the system itself, start with what is saju. For how the Korean practice differs from its Chinese sibling that models often blur together, read saju vs bazi. And if you arrived here looking for a Korean reading via ChatGPT rather than a prompt, that shorter piece is the better starting point.