Top 5 Zodiac Placements That Determine Compatibility When You Compare Birth Charts

Are you compatible for life — or is it just a fling?

couple in front of astrology wheel Maksym Azovtsev via Shutterstock / 2ufoto via Canva

Any two people can make a relationship work if they both really want to. No one is “destined” to be with anyone else in particular.

However, there are some couples who sure do make it look like they were created to be together, and others that make you wonder how they get through a day without killing each other.

Where do you and your partner fall on this scale? 

Astrology can tell you a lot about why your relationship is or isn’t successful.


When you compare your birth chart with your partner’s, there are a few things that will show whether you can expect your relationship to be one of the easy ones, or if you’re going to have a lot of work to do if you want to stay together.

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The technical term for a comparison between two charts is synastry. A synastry chart shows how certain astrology placements combine their energy in the twelve houses of the chart and the effects that the planets in both charts have on one another.

The synastry chart describes where you and your partner mesh really well. It will also give you a good idea of where your personalities clash the most, as well as what you can do to work through these rough spots.


Of course, there are so many combinations that a thorough interpretation can become quite complicated. When you put two charts together, it gets even deeper. A full synastry chart takes quite a while to read since it shows all the details and little nuances of a relationship.

Don’t be intimidated, though — you don’t need to be a professional to pick out the most obvious and important points.

Here are the five things to look at first when comparing birth charts for compatibility.

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1. The 7th house

This segment of the chart has to do with marriage and other deep, lasting partnerships. The qualities of the sign that rules this house can tell you a lot about the type of person who would be perfect for you.

For example, if Capricorn rules your 7th house, you should find someone who is patient, takes commitment seriously, and is willing to work hard to achieve their goals.

This does not mean that you should only limit yourself to dating Capricorns, though! The Sun sign describes the overall personality, but anyone can exhibit traits from any of the signs. Someone who has Capricorn as their Rising sign, or who has a lot of planets in Capricorn, for example, is naturally going to have a lot of Capricorn energy regardless of where their Sun is.

2. Venus placement

Venus is the planet of compassion and love. A person’s Venus sign tells you a lot about how they express romantic feelings and how they wish their partner would communicate these feelings.


If you and your partner’s Venus positions are in compatible signs, it will be easy for you to understand each other when you talk about your love for one another and your hopes for the relationship.

If the signs are incompatible, though, you’re both going to have to work on listening well, being very clear about what you want, and remembering to show your love in ways that will be understood.

3. Mars placement

Mars rules lust and passion. The Mars sign describes someone’s sexual comfort zone.

Compatible Mars signs can mean some unprecedented fun in the bedroom (or wherever)! If the Mars signs are incompatible, you both will have to be very clear about your physical needs and desires, and how far you’re willing to go to adapt to your partner’s preferences.


Be careful with Mars, though. This planet also rules anger, and there’s a fine line between passion and rage. Even when Mars signs are compatible, sometimes that energy can get out of control and grow into something very unpleasant.

4. Venus & Mars aspects

We’re not done with Mars and Venus yet! Because these two planets are so synonymous with love, sex, and romance, you also have to look at how they interact with each other and the rest of the planets across the two charts.

These planetary interactions are called “aspects.” There are a lot of different types of aspects based on the geometric angles between planets, but we’ll concentrate on two of the big ones: trines (positive) and squares (negative).

Trine aspects between one person’s Venus and the other’s Mars make for a beautiful relationship. But if Mars and Venus form a square aspect, the relationship may only function on one level: maybe you’re devoted to each other emotionally without a physical attraction, or maybe the sex is fantastic but you don’t really feel any connection beyond that.


5. How many aspects

Finally, take a look at how many aspects there are between all the planets across your two charts.

You don’t need to know how to interpret every one of them, just have a general idea of how many positives and negatives there are (any good charting program will show you which ones are which).

Obviously, a lot of negative aspects indicate trouble. But even a lot of positive aspects can be a problem: relationships that are too easy don’t give you much opportunity to grow as a couple and could get boring, fast.


If there are only a few aspects between your and your partner’s planets, you two might have a hard time finding much in common. A lot of aspects — positive or negative — suggest that you two will have many ways to help each other develop, and may even be together to continue a past life relationship.

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Trudi Mentior grew up in Great Falls, Montana, where she spent her formative years wondering just what might be beyond those vast plains, on the other side of those distant mountains. She now lives in Vancouver, Washington, with her husband, three cats, and a loudmouthed hyacinth macaw (who loves to scare the cats).