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Astrology and Romance Compatibility

There are several ways to find out how compatible you might be with someone else using astrology. Most of these methods are generally used for love relationships, but will also give you some information about how you interact with another person if they are a friend, family member or someone that you work with.

Below are some examples of ways you can check your astrological compatibility with someone else. I will be expanding on each of these methods in future articles.

The article below includes affiliate links to various items. If you click on one of those links and purchase an item, I may (at no extra cost to you) earn a commission. 

Synastry (comparing your planets to their planets)

Synastry is the term that is used for the comparison of the aspects between one person’s planets and chart points to another person’s planets and chart points.

In astrology, aspects are angles between planets. Trines and sextiles are usually considered beneficial and tend to have an easy, helpful energy to them.  Squares, inconjuncts (also known as quincunxes), and oppositions tend to have a more challenging or difficult energy to them and the conjunction can go either way.

Initially, it may be wise to just use the main aspects (conjunction, trine, sextile, square, and opposition).

When reading a natal chart, among other things, we look at the aspects between our natal planets and chart points and that tells us about ourselves. With relationships, by looking at the aspects between the two natal charts (called interaspects) we can tell a lot about the relationship.

Not knowing someone’s time of birth will mean that their Ascendant and Midheaven placements will not be known. As the moon moves up to 12 degrees in a day, you are unlikely to know the position of their Moon either. This makes using aspects to these parts of their chart unreliable. 

Planets in aspect

Aspects involving the Moon tend to be related to how we relate to others emotionally.

Aspects involving the Sun tend to be related to how we feel about ourselves.

Aspects involving Mercury tend to be related to communication.

Aspects involving Venus tend to be related to our values and how we give and receive affection.

Aspects involving Mars tend to be related to energy – our ambition, sex drive, and anger.

Aspects involving Jupiter tend to be related to our philosophy, enthusiasm, and generosity.

Aspects involving Saturn tend to be related to restrictions but also stability and longevity.

Aspects involving Uranus tend to be related to excitement, unpredictability, and unreliability.

Aspects involving Neptune tend to be related to romanticism, idealism, and deception.

Aspects involving Pluto tend to be related to intensity, passion, and destruction.

Aspects involving Chiron tend to be related to emotional wounds and healing.

Aspects involving the Ascendant tend to be related to how you are viewed by the world at large.

Aspects involving the Midheaven tend to be related to our career or public reputation.

Aspects involving the North Node tend to be related to what we need to be working towards.

The South Node is likely to bring a feeling of having known this person before. The Nodes (North and South) are also said to be related to karma.

Aspects involving the Vertex tend to be related to fated relationships.

Orbs for aspects

The likelihood of an aspect being exact is low, so an orb is usually given to allow for an angle being considered an aspect even if it is not at the exact degree.

A trine, for example, is 120 degrees but allowing an orb of 3 degrees either side widens that measurement from 117 to 123 degrees being considered a trine.

The closer the orb is to being exact, the more powerfully the aspect or interaspect will be felt. The orbs for synastry tend to be smaller than those for natal charts.

In his book Astrology A Language of Life – Volume IV Relationship Analysis, Robert P. Blaschke recommends using the following orbs in synastry charts:

  • 4 to 5 degrees for conjunctions and oppositions
  • 3 to 4 degrees for trines and squares
  • 2 to 3 degrees for sextiles
  • 1 to 2 degrees for quincunxes, semisquares, and sesquiquadrates
  • 1 degree for semisextiles, quintiles, septiles, and noviles.

The higher orbs are for aspects to the Sun and Moon (the lights) and the lower orbs for aspects to the planets.

It also helps to know both the natal charts well, as what may seem rather challenging to some, may not be so difficult for one or both partners. If someone has an aspect in their natal chart that is mirrored in the synastry chart, then, they may have a better understanding of the qualities of that combination and may be able to cope with it better than would usually be the case.

Synastry bi-wheels 

Below is a bi-wheel chart, with one person’s chart on the inside and the partner’s chart outside of it. Inside the middle circle, you can see the interplay of the interaspects (the red and blue lines) of both people. Sometimes you will notice that someone’s planet will help to complete an aspect pattern in the other person’s chart. If you are looking to find aspect patterns formed by two charts, you may need to use natal chart orbs rather than synastry orbs.
BiWheel astrology chart
A Bi-Wheel of two natal charts. The center has the interaspects of the charts.

Synastry grid

A synastry grid is perhaps an easier way to view the synastry between two people. A synastry grid like the one pictured below gives a clearer and cleaner (in my opinion) overview. You can miss out on seeing the aspect patterns that are formed by combining two charts though.
Synastry chart
Synastry chart with the interaspects between the two charts.

A synastry grid should usually show some good aspects within the top left-hand section (Mars to Mars – I have outlined these in red in the above image) as this is the interplay of the inner planets of one chart with the inner planets of the other chart.

These are good for the day to day interactions between two people but may not have enough staying power without Saturn or other outer planets making connections to the inner planets.

You would also like to see some connection between one person’s planets and the other person’s Ascendant/Descendant, MidHeaven/Immun Coeli, and Nodes.

When looking at romantic compatibility you would like to see aspects involving the Sun, Moon, Venus, and Mars. Saturn aspects help to lend stability to a relationship.

Pluto brings intensity and passion, Uranus some excitement and unpredictability. Neptune has us looking through rose-colored glasses more often than not, and Jupiter lends an exuberant and outgoing adventure-seeking side flavor to the pairing.

The number of interaspects in the whole grid will naturally be influenced by what aspects are used and what orbs were used for those aspects.

For example, I have used only the major aspects in the chart and grid above and the smaller orbs that Blaschke recommends. To help keep things simple, I haven’t included the quincunx, semisquare, sesquiquadrate, semisextile, quintile, septile, and novile aspects that he recommends.

How to find out you and your partner’s planets and chart points

You can find out your natal planets and your partner’s natal planets (if you know your and their time, place and date of birth) using a site like Astrodienst.

It’s free to set up your own chart and add many more. You can then go to the Free Horoscopes, Extended Chart Section and select Synastry Chart for the chart type.

Looking for more information?

If you are interested in exploring more about this, a good basic book is Linda Goodman’s Relationship Signs – it goes through and gives you a description for every combination of interaspect in synastry, and includes a listing of what combinations she considered signs of karmic relationships.

I would also recommend the Robert Blaschke book mentioned above if you have a good basic understanding of astrology ( the back of the book does say that it was written for professional astrologers and advanced students though).

I also thoroughly enjoyed his book on progressions. Blaschke recommends using synastry after a relationship has been in effect for six months or more.

For those that would prefer a chart and report already done up for them and their partner, we offer the Couple Report which is an astrological synastry report that also includes house overlays and synastry midpoints.

House overlays – where the planets in your chart fall in their chart (and vice versa)

This is quite a fun thing to do, it will give you an overview of how you and your partner influence each other. Blaschke comments in the above-mentioned book that this was the method he recommended to his students when looking at new relationships.

Astrology House Overlay method of looking at romantic compatility according to astrology.
Natal charts up the top. Synastry grid in the middle and the bottom charts are overlays in each other’s charts.

If you do not know someone’s time of birth, put their chart on the outside and your chart on the inside. This way it is your houses that are being used. Their planets will be correct for the most part, although their Moon can move up to 12 degrees in a day so you will be unsure of its exact position.

When you are not aware of someone’s time of birth, the general practice is to use 12 pm as the time of birth. If they have a general idea of when it was (morning, noon, night etcetera, naturally pick a time closer to that time but be aware that the Ascendant, house cusps and Moon will not be accurate).

Planets in each other’s houses

If you have a good basic understanding of the meaning of the planets and an understanding of the meaning of the different astrological houses, this will seem quite natural to you.

Basically, the characteristics of your planet are being imposed on their house (and vice versa). The houses can cover a wide array of areas, and the planets express their natures in different ways.

Ist House – relates to how we are perceived by others generally speaking.

2nd House – relates to our finances, possessions, and feelings of self-worth.

3rd House – relates to our siblings, communication, local neighborhood, and learning.

4th House – relates to our home and family, our ancestry and real estate.

5th House – relates to what we do for fun; our children, creativity, sport, love affairs, etc.

6th House – relates to our work, daily routines, health, and pets.

7th House – relates to our relationships, our partner (business and romantic) and open enemies.

8th House – relates to shared resources, taboo subjects, sex, and deep emotions.

9th House – relates to long-distance travel, philosophy, religion, beliefs, the law, and publishing.

10th House – relates to our career but also our public reputation, fame, and notoriety.

11th House – relates to our friends, groups that we belong to and our hopes and dreams.

12th House – relates to our hidden side, our undoing, this may be our self-destructive side or it could be where we are quite spiritual and or closed off to others generally.

Planets in the types of houses

Planets conjunct the other person’s angular houses will be more obvious in this format. Looking deeper into the houses, you can investigate who has more planets in different types of houses.

The angular houses are the 1st, 4th, 7th and 10th. Planets in these houses will have a stronger effect as these are houses that in general tend to be more obvious to others, and the closer one person’s planet is to the actual cusp, the more powerful it will be. Many planets in both charts being in angular houses suggest an active relationship where the partners enjoy being involved in activities together.

The succedent houses are the 2nd, 5th, 8th, and 11th and many planets in these houses for both charts may indicate a stabilizing and calming influence on each other.

The cadent houses are the 3rd, 6th, 9th, and 12th and when the majority of planets are in these houses for both charts it may indicate a relationship where communication and the exchange of ideas are very much a feature.

The houses can also be broken down into their elements, assuming that the 1st house is a fire house, the 2nd an earth house, the 3rd an air house and the 4th a water house.

This method would likely work best if the charts used didn’t have extra-wide houses as shown in Chris’s chart above. An equal house or whole sign chart system being used, rather than Placidus, as shown in the charts above, would probably be best in that case.

The 1st, 5th, and 9th houses are considered fire houses and will be similar to the qualities of Aries, Leo, and Sagittarius.

Someone having a planet in someone’s fire houses is likely to have a strong effect on the house person and this may manifest as affecting their appearance (1st), creativity (5th), beliefs or cause them to travel (9th).

The 2nd, 6th, and 10th houses are considered earth houses and will be similar to the qualities of Taurus, Virgo, and Capricorn.

Someone having a planet in someone’s earth houses is likely to have an impact in some financial or career oriented way. The house person may benefit financially or materially (2nd), through some service that the planet person provides (6th) or in their career in some way (10th).

The 3rd, 7th, and 11th houses are considered air houses and will be similar to the qualities of Gemini, Libra, and Aquarius.

Someone having a planet in someone’s air houses is likely to expand the house person’s communications in general (3rd), feeling of being understood (7th) and mixing with others (11th).

The 4th, 8th, and 12th houses are considered water houses and will be similar to the qualities of Cancer, Scorpio, and Pisces.

Someone having a planet in someone else’s water houses is likely to have an emotional impact. While planets in the 4th house may relate more closely to the planet person’s relationship with the house person’s family and home, planets in the 8th house are likely to be related to deep issues of the house person.

Planets in the 12th house may bring assistance in dealing with problems that have been self-limiting for the house person.

How to find a chart with your house overlays

If you go to Free Horoscopes and then the Extended Chart Selection on the Astrodienst site you will be able to erect a chart with your chart inside and their planets on the outside (called Natal with Partner Outside).

Looking for more information?

The book Synastry by Ronald Davidson has a section on what it means to have your planets in the other person’s houses. This author is also the developer of the Davison Chart (see below) so it explores that as well.

Composite Charts (the midpoints of both natal charts)

The Composite Chart is a relationship chart that takes the midpoints of each of your natal planets and charts points to form a new chart for the relationship. Blaschke, recommends that a Composite chart is not used until a relationship has been in effect for a year or more.

Composite chart used to look at astrological compatibility of a couple.
A composite chart is erected using the midpoints between two chart’s planets, luminaries and chart points.

The Composite Chart is an entity in and of itself

The Composite chart is meant to be read in a similar fashion to a natal chart. The house position of the planets and the aspects between them will tell a lot about the relationship and how it operates.

However, as it is a chart with no time or place for when it is cast, it will sometimes have features that would be impossible in an astronomical sense, such as Mercury or Venus opposite the Sun.

In the chart above I have used the same charts I have been using all along. As Chris’s Ascendant was at 16 degrees Capricorn and Marie’s Ascendant at 26 degrees Capricorn, the midpoint Ascendant was 21 degrees Capricorn.

Similarly, as Chris’s Sun was at 28 degrees Libra, and Marie’s Sun was at 8 degrees Aries, the midpoint Sun was 18 degrees Capricorn ( the midpoint is taken via the shortest route, which is why the Composite Sun was not Cancer in this case). These calculations are made for all the rest of the planets and will include the Midheaven.

In the chart above, both people had a natal Capricorn ascendant and ended up with a Composite Capricorn Ascendant. If one were to have a natal Aquarius Ascendant and the other a natal Libra Ascendant, they may have ended up with a Composite Sagittarius Ascendant.

In the first case, as both have a Capricorn Ascendant, they may not change much in regards to how they present themselves to the outside world (Ascendant) as a couple. This is because they already individually operate like this because both of their Ascendants are in Capricorn and that is how they both go about presenting themselves to the outside world as individuals.

The second couple may find that they are perceived (Composite Ascendant) as being more adventurous and outgoing (Sagittarius) as a couple than they are as individuals. When in a relationship, the way they present to the world is in a Sagittarian (Composite Ascendant) manner rather than the Aquarian (natal Ascendant) or Libran (natal Ascendant) manner that they do individually. This is not better or worse, just that the couple presents in a different manner because they are in a relationship with each other.

Planets in the 1st house along with aspects to the Ascendant and planets in the 1st house will also give information about how this couple is seen by others.

In a similar fashion, planets and aspects to planets in the 2nd house will tell how the couple approaches finances and possessions. The 3rd house will give clues to their communication styles and so on through all the houses.

The Composite Chart and natal chart contacts 

It is not uncommon to find Composite planets or angles closely conjunct one of the persons natal planets or angles. For example, in the chart above, the Composite Moon at 27 °58′ Capricorn is just over one degree away from Marie’s natal Ascendant of 26 °42′ Capricorn (the measurement after the degree symbol is the minutes, so it is 16 minutes out from being 1 degree away).

The Composite 10th house cusp, also known as the Midheaven at 29°14′ Libra is just over one degree away from being conjunct Chris’s natal Sun at 28 °07′ Libra (the degrees are 1 degree apart but the second part, is out by 7 minutes).

Chris may find that he feels more confident and secure in himself (natal Sun) and his public reputation (Composite Midheaven) because of the relationship. Meanwhile, Marie may find that how the relationship affects her emotionally (Composite Moon) may have some effect on how she is perceived by others (natal Ascendant).

Transits to the Composite Chart

You can also use transits to the Composite chart to see how the relationship progresses just as you would use transits to a natal chart to see what events you might expect to develop for an individual.

You would expect to see contacts to planets or angles in the composite chart for significant events in the relationship such as the first meeting, engagement, wedding etcetera.

Composite astrology chart. with transits
Composite chart of the couple in the middle, transits in the outer chart

In the chart above, the Composite chart of Chris and Marie is the inner chart and the outer chart is the transits for the time and place of their first meeting. The initial meeting should have been for the day before but an emergency landing on an international flight delayed the meeting until the next day (never a good idea to travel during Mercury retrograde if you can help it).

At the time of their first meeting, transiting Venus was conjunct the Composite chart Descendant (7th house cusp and associated with relationships) as well as one degree away from the Composite Venus. If they had met the day before as planned, transiting Venus would have been just out of orb to conjoining the Composite Descendant (allowing a one-degree orb).

Transiting retrograde Mercury was conjunct the Composite Uranus in the 8th house. Transiting Uranus was one degree away from the Composite Imum Coeli (IC), the 4th house angle related to our family and most inner private self.

As transiting Uranus had just stationed retrograde and started moving away from the Composite IC, it will first cross the Composite IC very early in May 2018 in direct motion. Uranus will transit retrograde over the Composite IC again in late November 2018 and then cross it one last time in direct motion in mid-February 2019. It may then create havoc in the 4th house of home and family but will not cross the Composite IC anymore after that.

As you can see, the outer planets can have quite an effect on relationships and when they are crossing angles such as the Ascendant, IC, Descendant or Midheaven they are likely to be significant.

As they are often retrograde, it is not unusual to have three crossings of the angle;  when they first pass over the degree in direct motion, then when it retrogrades over the degree again and then finally when it goes direct and crosses that degree the last time. Allowing a degree of one orb for transits and progressions will widen the time span that significant events may fall.

Where to find your Composite Chart

Astrodienst provides free natal charts as well as the ability to erect composite and other relationship charts. You need to enter the chart details for both persons and then select Extended Chart Selection under the Free Horoscopes section. You will then need to select a composite chart, midpoint method as the chart type.

Looking for more information?

This article by Liz Green is rather informative and has me curious to read her book Relationships and how to survive them.  Astodienst also offers a breakdown of the aspects in a Composite chart if you look under Free Horoscopes, Interactive Horoscopes and then AstroClick partner.

Davison Charts (finding the middle date and place of your births)

The Davison Chart is another relationship chart but this one takes the birth dates of each person and selects the middle date in between the two. Similarly, the two birthplaces are taken and a place in the middle of the two is selected, even if that place is in the middle of the ocean. From this middle date and place, a new chart is erected and this gives some indication of how the relationship might work.

A Davison chart, between Marie and Chris
A Davison chart, erected for the middle of both people’s date of birth and for the middle of each person’s place of birth.

The chart above is a Davison chart for Chris and Marie, the two charts I have been using throughout this article. Marie was born on the 30th of March 1967 and Chris the 21st of October 1961. The date for this chart is the midpoint of those two birthdates, namely the 10th of July 1964 (when partners were born in different time zones, you need to take this into account).

The middle of both places of birth was also taken and used to cast this new chart, in this case in the middle of the Pacific ocean as Marie was born in Australia and Chris in the United States.

You may notice that this chart also has a Capricorn Ascendant, which is the same sign as the Composite chart as well as the two natal charts. This will not always be the case, sometimes a different Ascendant will be given for the Composite and Davison charts which may be different from either natal Ascendant.

The Ascendant differs by a few degrees between the Composite and the Davison charts but the Midheaven and IC (4th house cusp) remain at 29 degrees Libra and Aries for both. As such the Davison Midheaven is just over one degree away from conjuncting Chris’ natal Sun at 28 degrees Libra.

The moon in the Davison chart is just out of the one-degree orb for being conjunct Marie’s Descendant at 26 degrees Cancer.

Secondary progressions and transits to the Davison Chart

Blaschke believed that the Composite chart represented the relationship as a separate entity in and of itself while the Davison showed areas where others may try to influence the relationship.

While Blaschke recommended paying attention to the sign placement and essential dignity of the planets and lights for the Davison chart he didn’t for the Composite Chart. The Davison chart can also have transit and secondary progressions run against the chart.

A Davison chart with transits and secondary progressions.
avison relationship chart (inner) with secondary progressions (middle) and transits (outer) for the date of the first meeting.

Looking at the secondary progressions (middle chart) and transits (outer chart) to the Davison chart (inner chart) brings up some interesting contacts.

The secondary progressed Venus was conjunct the Descendant (7th house cusp) at the time of the first meeting, which seems appropriate and the transiting Venus was not far behind it.

Transiting retrograde Saturn was within one degree of opposing the Davison retrograde Venus but stationed direct before it had a chance to reach exact opposition.

Transiting retrograde Pluto was opposite the Davison Sun,  and transiting Uranus was within one degree of being conjunct the Davison IC (and also opposed Chris’s natal sun).

Transiting Jupiter in the 9th house of long-distance travel was exactly quincunx (degree and minute) the Davison Jupiter in the 4th house of home and family. Quincunxes often require adjustments to be made.

Interestingly, the Davison secondary progressed retrograde Mercury conjunct the Davison secondary progressed Uranus at the same degree, are both conjunct the transiting retrograde Mercury for the time of the first meeting. This is the same degree that the Composite Uranus is at.

Uranus is quite significant in the relationship as the pair met online (Uranus) and live in different countries which makes it difficult to have a “normal” relationship and throws up significant difficulties to overcome.

Sabian Symbols

Sometimes looking up the Sabian Symbol for a degree can give some extra insight to a chart.  When looking up Sabian symbols, you take the next full degree. So Uranus at 28 °Aries 25′  will match the Sabian symbol for 29 degrees Aries, “A celestial choir singing”.

The Sabian symbol for 11 Virgo (Davison secondary progressed Uranus conjunct Davison secondary progressed retrograde Mercury as well as the transiting retrograde Mercury) gives the  symbol of “A boy molded in his mother’s aspiration for him.” As family responsibilities on both sides keep Chris and Marie apart, for the time being, this degree seemed rather telling.

For those interested in exploring Sabian Symbols more, Lynda Hill has an excellent site and book about them.

Retrograde planets

Unlike the composite chart, the Davison chart will have retrograde planets and these may prove significant, for understanding the dynamics of the relationship, but also may be quite significant when a retrograde planet turns direct by secondary progression.

In the Davison chart above, Venus is retrograde in the 5th house, but it turned direct by secondary progression before Marie was even born. The secondary progressed Venus stationed direct and crossed the exact degree of the Davison Venus in late January 1967 and was still at that degree at the time of Marie’s birth (30 March 1967).

Mercury is direct in the 7th house of the Davison chart but turned retrograde by secondary progression in early December 2004 in the 8th house. It will turn direct by secondary progression late January 2028 in the 8th house.

Saturn is also retrograde in the 2nd house of the Davison chart, but will not turn direct by secondary progression until 2080.

How to find your Davison Chart 

Astrodienst allows you to erect your own natal chart and those of others and you can erect a Davison chart by selecting their Free Horoscopes, Extended Chart Selection and then selecting Davison Relationship under the chart type.

Looking for more information?

For the more advanced astrology enthusiast, I would recommend Robert Blaschke’s Relationship Analysis (Astrology: A Language of Life, Vol. 4)

Ronald Davison’s Synastry: Understanding Human Relationships Through Astrology is written by the developer of the Davison Chart system and includes information on house overlays.


Born and bred in Brisbane, Australia, I have had a fascination with astrology since I was a child. I hold the STA’s Practitioners Level Certification in Horary and am currently studying Hellenistic Astrology.