What Two Charts Can Honestly Say About Two People
Compatibility tables are the most-read and least-defensible thing in popular astrology. Two entire charts — twenty-odd placements between them — reduced to a percentage or a verdict, on the basis of one placement each.
The tradition’s own approach to comparing two charts is considerably more involved and considerably more interesting, and it starts by not asking whether two people are compatible.
Why the table fails
Not because Sun signs mean nothing, but because one out of ten bodies cannot carry the weight being put on it.
Two people with supposedly clashing Suns can have Venus and Mars placements that fit together without friction. Two people the table declares ideal can have Moons that need completely incompatible things. The table cannot see any of this, because it never looked.
The deeper problem is the question itself. “Are we compatible” invites a yes or no about something that is not a yes-or-no matter. The tradition asks instead: where will these two find each other easy, and where will they have to do actual work? That question has a useful answer.
The four things worth comparing
Moon to Moon. The most informative comparison and the one the tables never make. Moons describe what each person needs in order to feel settled. Two people can enjoy each other’s company enormously and still need opposite conditions to recover — one needing company after a hard day, the other needing an empty room. That is not a failure of affection; it is a structural difference, and knowing about it in advance is worth more than any verdict.
Venus to Mars. Each person’s Venus against the other’s Mars. Venus is what someone is drawn to; Mars is how the other pursues. Where one person’s pursuit matches what the other is drawn toward, attraction has somewhere to land. Where it does not, both people can be entirely willing and still keep missing.
Mercury to Mercury. How two people process and explain. This is the placement that governs whether conversations resolve or circulate. An earth Mercury wanting the specifics and an air Mercury wanting the principle can have the same argument for years without either noticing they were answering different questions. It sounds less romantic than the others and it accounts for more day-to-day friction than either.
Saturn contacts. Where one person’s Saturn touches the other’s personal placements, the tradition reads durability and weight — and also constraint. This is the pairing associated with relationships that last and that demand something. It is not comfortable and it is not supposed to be.
The element reading, which is coarser but useful
A quicker approach that holds up reasonably well: compare each person’s overall elemental balance rather than individual placements.
Two heavily fire charts share momentum and have nothing between them that says wait. A fire chart with an earth chart produces the familiar pairing where one starts things and the other finishes them — genuinely complementary, and a reliable source of mutual irritation. A chart missing an element paired with one carrying plenty of it is one of the more interesting combinations the tradition describes.
Our elemental weather calculator gives a weighted distribution for each person, which is the input this comparison actually needs.
What none of this does
It does not predict whether a relationship will work. It does not identify who you should be with, and it certainly does not identify who you should leave.
Charts describe dispositions. Relationships are made of what two people do, repeatedly, over time, and no placement determines that. A chart comparison can tell you where the friction is structurally likely — and that is genuinely useful, because knowing that a disagreement is about processing style rather than about caring is often the whole difference.
Used the other way, as a verdict, it becomes a reason to abandon something workable or to persist with something that is not. That is a misuse, and it is the most common one.
Doing it properly
You need both charts, which means both sets of birth details. The star map computes a full chart from date, time and place, and Venus, Mars, Mercury and usually the Moon are available even where the hour is not known.
Our compatibility section works from more than the Sun for the reasons set out above. And if you want to understand what you are comparing before you compare it, the planets section of the almanac covers what each of these placements traditionally governs.