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Ask a model about a co-founder, not about a couple
The server builds both charts, finds the contacts running between them and scores five domains of a working relationship, then packs it into one block of text.
You are weighing someone as a co-founder, a partner in a small firm, or the first hire who will hold a piece of the company. Put that to a chat window and it answers from two sun signs, because two sun signs are all you gave it.
This page gives it something to work from. Enter both births; the calculator builds the charts on the server, tests each body of one against each body of the other, scores five domains of a working relationship out of 100, and writes it out as plain text. Paste that into ChatGPT, Claude or any model, and the answer is about the two people in front of you.
What a chat window cannot work out about a partner
Two things stand between an assistant and a usable answer. The first is astronomy: where Mercury or Saturn stood over a city at a given minute is a table lookup, and a model asked for one hands back a plausible wrong number. The second is bookkeeping: a hundred body-to-body pairings, each kept or dropped by how far it sits from an exact angle, then ranked by that gap.
A third gap belongs to business questions alone. A working relationship is never one thing: two people can argue their way to good decisions and still miss every deadline. So the text arrives split five ways, each domain anchored on a planet: Mercury carries communication, Saturn reliability, Mars drive, Jupiter and Venus growth, the Sun goals.
Get your business synastry prompt
Enter both partners' birth details — we compute both charts, the contacts between them and the five-domain business score, and hand you the text to paste into your AI.
Person A
Person B
How to get your reading
Enter both partners
Two forms, with the fields the business synastry calculator already uses: name, date, time, place. The place lookup supplies the coordinates and the time zone offset for that date. If one of the two hours is unknown, mark it unknown rather than rounding it to nine.
Build the prompt
One button. Both births go to the server, which returns the two computed charts; the contacts between them and the five domain figures follow, and everything is assembled into a single block you copy in one piece.
Paste it as your opening message
Send the block as the first message of a fresh conversation. Its closing instructions keep the model on the working relationship, hold it to the positions it was given, and ask for recommendations at the end, so nothing needs adding underneath.
Ask the second question
The first answer is a survey. The useful part begins when you name a decision you face: who signs off on spending, who handles the client, what happens when one of you wants to grow twice as fast.
What is inside the block
Both charts arrive first and complete: every body with its sign, degree and house, retrograde markers, the angles, the cusps, each person's own aspects. Then comes the part that exists only once there are two people: each contact running from one chart to the other gets its own row, tightest first, labelled so a link between you is never mistaken for an aspect inside one chart.
The score block closes the data: an overall figure and one per domain, each printed out of 100 with the number of contacts behind it. Under that sit the instructions. They confine the reading to work and rule out romance, chemistry and family life; they require every claim to rest on a contact from the list; and they ask for advice on writing the agreement, splitting responsibility and handling disagreements.
Holding the model to roles and money
An answer saying you complement each other has told you nothing. Insist on a division of labour: who holds the final word on spending, who runs the client conversation, who is the brake and who is the accelerator. The Saturn contacts are where the first answer lives; the Jupiter and Venus ones build the growth domain.
Make it show its working. Every row carries an orb, and the orb is the hierarchy of the reading: a link closing to within a degree does far more than one four degrees wide. A paragraph about money naming no contact and no orb is decoration.
This is not the love synastry prompt
The two pages take the same two births and part company immediately afterwards. A romantic reading is weighed on the Moon, Venus, Mars and the lunar nodes; this one never asks those bodies for a couple's story, and its instructions forbid the model from writing about attraction or family life even where the charts invite it. If the relationship rather than the venture is what you came for, the synastry prompt is the page to open instead. The split is practical: this assessment is worth having only if it can be blunt about unreliability.
Reading the score block for what it is
Each domain starts at 50, the neutral value for a domain with nothing said about it, and moves as contacts to its anchor planet accumulate. The overall figure is the rounded mean of the five, so one tense domain never sinks the pair and one strong domain never rescues it. A single contact can move two domains: a Mercury to Saturn link touches the communication anchor and the reliability anchor, and counts in both.
The text itself calls that block a heuristic and a starting map, and tells the model to ground conclusions in the contacts rather than the figures. A domain at 74 out of 100 says where to look first; the finding is the contacts underneath.
Where this stops
It will not tell you whether to sign. No arrangement of planets knows the market, the runway, or whether either of you has run anything before. Take the output as a description of how friction will reach you, then hold it against the months the two of you have already worked together.
The positions are computed; the reading is still a model's writing, and models fill gaps with confidence. Push back: what in the list produced that sentence? An assessment finding nothing difficult has stopped halfway down the list.
Questions
It works without them, at a cost worth knowing first. One unknown birth time strips the houses and the angles out of both charts, not only out of the one whose hour is missing: the reading covers both partners at once, so that layer drops for the pair. The contact list and the domain figures survive, because a body's place against another body is set by the date.
No, and reading it as one wastes the rest. It is the rounded mean of five domain figures, each of which began at the neutral 50 and moved with the contacts to its anchor. A pair at 62 with solid reliability and strained communication differs from one flat at 62.
The arithmetic does not care what the relationship is called, and the five domains fit a key hire as well as a co-founder. Two cautions: their birth data is theirs to give, and a test nobody agreed to is a poor basis for a decision about their pay.
Classical bodies only, one anchor per domain: Mercury for communication, Saturn for reliability, Mars for drive, Jupiter with Venus for growth and money, the Sun for goals. The Midheaven is often called the career point, but it is an angle rather than a body and no contacts to angles are computed, so goals rest on the Sun.
Usually the block went in half-pasted, so the instruction ruling romance out never arrived. Send it whole, in one message; if it drifts even so, reply that the subject is the working relationship and ask for that section again.
Ask in those words. With the reading on screen, ask which three clauses this pair should put in writing before starting, and what the early warning sign of each named risk looks like in an ordinary week. That works better as a second question than folded into the first.