Free Composite Chart Calculator
Build the midpoint chart of two people. The composite describes the relationship as its own chart — separate from either person’s natal chart.
Free to calculate — no sign-up. Sign in to save charts and unlock the Deep Report.
What a composite chart is
Take each planet in both birth charts and mark the halfway point. Those midpoints become one chart: the composite. It does not say how you treat each other. It says what the relationship is like when it is treated as a third thing — a shared life, a business, a family unit.
That is why the same two people can have a warm synastry and a demanding composite, or the reverse. Synastry is the conversation between you. The composite is the room you are standing in together.
How to Read a Composite Chart in 4 Steps
1. Start With the Composite Sun
The composite Sun is the midpoint of the two natal Suns. It is the purpose of the relationship when the two of you act as a pair, not what either person wants alone. Read the sign first. A Cancer composite Sun organizes the bond around a private base. A Capricorn composite Sun organizes it around a structure that has to last. This placement does not expire. It is the identity of the chart, not a transit of the month.
2. Then the Composite Moon
The composite Moon is the climate of an ordinary day inside the relationship: what feels safe, what feels exposed, how fast a mood is allowed to pass. It is smaller than the Sun and closer to Tuesday. If the Sun and Moon disagree, the bond can have a clear job and an uncomfortable daily feeling at the same time. That is not a contradiction in the method. It is two different questions.
3. Then Composite Venus and Mars
Venus is how the relationship shows care. Mars is how it pursues, argues, and gets something done. Read them as a pair. Easy Venus with a hard Mars means affection is available and the push is clumsy. Do not collapse them into one “chemistry” score. Synastry Venus–Mars is how the two people spark each other. Composite Venus and Mars are the affection and drive that belong to the bond itself.
4. Then Composite Saturn
Saturn is where the relationship asks for time, duty, or a boundary. A strong Saturn often marks a bond that lasts because it is structured, not because it is easy. A square from composite Saturn to the composite Moon can feel like criticism of the mood. It can also be the spine that keeps the climate from drifting. Do not read Saturn as a prediction that the relationship fails, and do not skip it because the Sun looks warm.
Houses and the composite Ascendant count only when both birth times are real. Planet-sign midpoints still form without a time. If a time is a guess, stay with the planets above.
Composite, synastry, or transits
- Synastry chart — how your planets aspect theirs. Use this for chemistry and friction.
- Composite chart — this page. Use it for the relationship as one chart.
- Transit chart — how today’s sky hits a natal chart. Pair it with the yearly forecast when you want the longer timing.
- Synastry vs. composite guide — a longer comparison if you are choosing which chart to run first.
- Birth chart without a birth time — which composite houses you can trust when a time is missing.
Example: Composite Sun in Cancer
A composite Sun in Cancer means the midpoint of the two natal Suns falls in Cancer. The relationship’s purpose wears a Cancer style: a private base, caretaking, and a preference for what can be felt at home over what can be performed in public. The pair may still have careers and friends. The chart is saying the bond itself is organized around shelter.
Scale: this is the identity of the relationship for as long as these two charts are the pair. It is not “Cancer season” and it is not a transit that ends in a month. It also does not prove the two people will live together or have a family. A composite describes the pattern. It does not issue the event.
Example: Composite Saturn Square the Composite Moon
Now a harder contact inside the same chart. Composite Saturn square the composite Moon is about 90° between the relationship’s limit and the relationship’s mood. Duty, time, or a rule keeps meeting the need to feel safe. On an ordinary Tuesday that can feel like criticism of a feeling, or like a mood that will not fit the plan.
This square does not last “a few weeks.” It is part of the composite, so it belongs to the relationship, not to this month’s sky. If you want the weeks when it gets louder, that is a transit to the composite — open the transit chart. The Sun example is what the relationship is for. The Saturn–Moon square is how a hard day inside it tends to feel. Read both. Do not let the square cancel the Sun, and do not let a warm Sun erase the square.
Composite by Planet
Each midpoint is one planet in the relationship chart. Read it before mixing them into a score.
- Composite Sun — the purpose of the pair. What you are building when you act together.
- Composite Moon — the daily emotional climate. What an ordinary day in the bond feels like.
- Composite Mercury — how the relationship thinks and repairs a conversation.
- Composite Venus — how the bond shows care, taste, and affection.
- Composite Mars — how the bond pursues, argues, and gets something done.
- Composite Jupiter — where the relationship makes life feel larger, or promises more than it keeps.
- Composite Saturn — the limit, the duty, and the structure that either holds or feels heavy.
Composite by House (1st – 12th)
A composite house says where the relationship spends its life. It is usable only when both birth times are documented. Without them, stay with the planet signs.
- 1st — how the relationship enters a room.
- 2nd — shared money, skills, and what the bond keeps.
- 3rd — talk, errands, the daily mind of the pair.
- 4th — home and the private base.
- 5th — play, children, romance, creative risk.
- 6th — chores, health habits, the work of maintenance.
- 7th — the bond facing other agreements and the public pair.
- 8th — shared debt, intimacy, what is not only one person’s.
- 9th — belief, study, and the story of the future.
- 10th — reputation and the role the relationship plays in public.
- 11th — friends and the wider circle around the pair.
- 12th — what the relationship keeps out of view.
Composite Questions
Composite vs synastry. Synastry keeps two charts and asks how they touch. The composite folds them into one midpoint chart and asks what the relationship is. Run synastry for chemistry. Stay here for the third chart.
Composite vs Davison. A Davison chart is the chart of the midpoint in time and place — a calculated moment. This page is the midpoint composite: each planet halfway between the two natal positions. They are not two names for the same chart.
For marriage. Weight the composite Moon and Saturn above the first impression of Venus. A marriage question is the Tuesday, plus whether a structure can hold it.
For a business. Read composite Mercury, Mars, and Saturn: how the partnership decides, pushes, and carries the unglamorous job. A warm Venus does not answer a contract question.
Composite chart questions
What is a composite chart?
A composite chart is the midpoint chart of two birth charts. Each planet is placed at the midpoint between the two people’s positions, so the result describes the relationship itself rather than how one person affects the other.
How is a composite chart different from synastry?
Synastry compares two natal charts: Person A’s Venus to Person B’s Mars, and so on. A composite folds those two charts into one midpoint chart. Use synastry for chemistry between you. Use a composite when you want the relationship as its own entity.
What does the composite result page show?
After you submit both birth details, Astro Seek calculates the nearer midpoint of each planet pair and lists composite Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn. That list is free. The longer written reading is separate. From the result you can move to synastry or transits.
Do I need exact birth times?
Exact times make the composite Ascendant, Midheaven, and houses meaningful. Planet-sign midpoints still form without a time, but house-based statements should be treated as provisional. If a time is unknown, read the birth-time guide before trusting angles.