Synastry bi-wheel
Partner A’s chart inside, Partner B’s planets and angles on the outer ring, with the cross-aspects drawn through the centre.
Partner Astro · Function 04
Synastry chart calculator.
Compare two birth charts for compatibility: one chart laid around the other, every cross-aspect between you, whose planets fall in whose houses, and a written partnership analysis for the topics you choose.
Two saved profiles·Cross-aspects with orb control·Analysis by topic
What you get01 02 03 04
Birth chart compatibility, drawn rather than guessed.
Every cross-aspect
Conjunctions, sextiles, squares, trines and oppositions between one person’s planets and angles and the other’s, sorted by exactness, with contacts inside 1° flagged.
House overlays, both ways
Where Partner A’s planets fall in Partner B’s houses, and the reverse, so you can see which areas of life each person activates for the other.
Partnership analysis
A written analysis of the pair for the topics you pick: overall compatibility, communication, emotional bond, romance and attraction, conflict and growth, commitment and longevity.
How it works
Two profiles, one wheel.
01
Save two profiles
Each person needs a birth profile: date, time and place. Both stay private to your account.
02
Choose Partner A and Partner B
Pick any two saved profiles. Swap them to read the overlays from the other side, and set the orb you want for the cross-aspects.
03
Read the contacts and generate the analysis
The aspect list and overlays update instantly. Choose the topics and the analysis is written from this pair’s actual contacts.
Compatibility beyond Sun signs
Sun-sign compatibility compares two signs. Synastry compares two whole charts: twelve bodies and four angles each, and every aspect between them. Moon to Moon shows how two people feel at home; Venus and Mars describe attraction; Saturn contacts show where the relationship asks for patience and where it can last.
natalGPS calculates both charts with the same zodiac and house system, so the comparison is consistent, and shows how many contacts fall within one degree, where the strongest themes usually sit.
How to read a synastry chart
Start with the closest cross-aspects, then the house overlays: a partner’s Sun in your seventh house or their Moon in your fourth carries meaning that no aspect list shows on its own. Then read the whole against the two natal charts, which natalGPS keeps a click away.
The partnership analysis follows the same order and is written as reflection on the pair, not as a verdict on the relationship.
- Works for romantic partners, friends, family and business pairs
- Orb from 1° to 10° for the cross-aspects
- Analysis stored per pair, regenerate any time
The synastry aspects that matter most
Cross-aspects describe how two charts touch. natalGPS lists all of them by exactness and flags those within one degree; these are the ones astrologers look at first.
- Sun–Moon: the classic marker of ease between two people
- Moon–Moon: how you feel at home together and handle daily life
- Venus–Mars: attraction and chemistry
- Sun–Saturn and Moon–Saturn: commitment, responsibility and the risk of feeling judged
- Venus–Pluto and Mars–Pluto: intensity, obsession and transformation
- Mercury contacts: whether you understand each other
- Ascendant contacts: instant recognition and how you present as a pair
- North Node contacts: a sense of fate or direction
House overlays: whose planets land where
Overlays show which area of your life the other person activates. Their Sun in your seventh house makes them feel like a partner; their Moon in your fourth brings them into your home life; their Venus in your fifth is romance and play; their Saturn in your tenth can be a mentor or a critic; their planets in your eighth or twelfth pull the relationship into deep, private territory. natalGPS shows both directions side by side, because a relationship rarely looks the same from each end.
Synastry versus composite and Davison charts
Synastry compares two complete charts and is the standard tool for compatibility. A composite chart builds a single chart from the midpoints of the two, and a Davison chart casts a chart for the midpoint in time and space; both describe the relationship as a third entity. natalGPS calculates synastry today, with composite and Davison charts planned.
Reading compatibility honestly
No synastry chart is a verdict. Hard aspects between two charts are where a relationship does its growing, and easy ones are where it rests; a pairing with only trines can be pleasant and dull, one with only squares exhausting. Read the cross-aspects against each natal chart, notice what each person already carries, and let the partnership analysis frame the themes rather than decide for you.
Questions
Partner Astro: frequently asked
Is synastry accurate for compatibility?
It is accurate about the geometry between two charts. Whether that geometry becomes a good relationship depends on the people. Treat synastry as a map of dynamics, not a score.
Do Sun signs matter in synastry?
They are one contact among dozens. A Sun–Sun square between two charts is real, but a Moon–Venus trine and a Saturn contact to the Ascendant often say far more about how the pair actually works.
Is there a synastry score?
natalGPS deliberately shows counts, orbs and overlays rather than a single number. A score hides the texture that makes synastry useful; the partnership analysis describes it instead.
What is a synastry chart?
A synastry chart overlays two natal charts to show the aspects between them and where each person’s planets fall in the other’s houses. It is the standard tool for astrological compatibility.
Is synastry the same as a composite chart?
No. A composite chart is a single chart built from the midpoints of two charts. natalGPS calculates synastry, the comparison of two complete charts; composite and Davison charts are planned.
Do both people need an exact birth time?
For the house overlays and the angle contacts, yes. Planet-to-planet aspects still work with an approximate time; a chart with an unknown time takes part without houses.
Which aspects matter most?
The closest ones, and those involving the Sun, Moon, Venus, Mars, Saturn and the angles. natalGPS sorts the list by exactness and flags every contact within one degree.
Can I compare friends or business partners?
Yes. Synastry reads any pair of charts. The analysis topics such as communication, conflict and growth, and commitment apply to every kind of relationship.