Find Your Ideal Partner with Synastry
Enter your date of birth, and the calculator will compare your Sun, Moon, Venus, Mars and other planets with the planets of every day in the years you choose and show who you share the strongest attraction aspects and the least friction with.
The calculator goes through every day in the years you choose; this takes about a second. Don’t know your birth time? Clear the field.
What the Calculation Shows
- Your planets — the signs of the Sun, Moon, Venus, Mars and the other planets, and, if the time and place of birth are known, of the Ascendant too.
- The most compatible date — the day in the selected years with the highest score, the part of the day when it is at its best, the partner’s Sun, Moon and Venus signs, the age difference and the main aspects between your planets.
- Four scales — attraction, emotions and comfort, communication and reliability: how much the aspects of each group contributed.
- What to look for in a partner’s chart — the signs in which the partner’s Venus, Moon and Sun give the highest score with you on average, and the one that gives the lowest.
- Fifteen best dates — each can be opened in the full couple compatibility reading.
- Aspects to avoid — the tense aspects that occur most often in the least compatible dates.
How it is calculated
Synastry is the comparison of two charts: which planets of one person form aspects to the planets of the other. The calculator takes the real positions of your planets and compares them with the planets of every day in the selected years. Five major aspects are counted: the conjunction (up to 8°), the opposition and trine (up to 7°), the square (up to 6°) and the sextile (up to 4°). The more exact the aspect, the more weight it carries.
The planet pairs are divided into four groups. Attraction: Venus with Mars, the Sun with the Moon, Venus with Venus and the Sun, Mars with the Sun, the Moon and Mars, and also the partner’s Venus to your Ascendant. Emotions: the Moon with the Moon, Venus and Jupiter, and the partner’s Moon and Sun to your Ascendant. Communication: Mercury with Mercury, the Sun, the Moon, Venus and Jupiter. Reliability: Saturn to the Sun, the Moon and Venus, Jupiter to the Sun and Venus, Mars with Saturn, Pluto to the Moon and Venus. Harmonious aspects add points. Squares and oppositions from Saturn, Pluto and Mars to the personal planets take points away; the exception is Mars with Venus, whose tense aspect adds attraction. Points are also taken away by squares and oppositions of the Moon to the Moon and Venus, of Mercury to Mercury, the Sun and the Moon, and of Venus to Venus. The percentage converts the date’s score to a scale from 1 to 99 using our formula: the more exact harmonious aspects, the higher it is.
The partner’s birth time is unknown, and the Moon travels about 13° a day. So each day is calculated for four parts of the day — night, morning, afternoon and evening — in the time zone of your birthplace. The day’s score combines the average of all four parts and the best of them.
If your birth time is not given, positions are taken for noon and aspects to the Ascendant are not counted. You can compare your chart with a specific person in Couple Compatibility.
An Honest Look at the Method
Synastry has no single scale: astrologers weigh aspects and orbs differently. The weights here are our own, based on generally accepted rules, so the percentage compares the dates with one another rather than measuring a future relationship. Studies that compared the birth dates of thousands of married couples found no link between astrological compatibility and who marries or divorces whom. The most compatible date is a reason to take a closer look, not a verdict and not a guarantee.
Frequently asked questions
Why does the best date sometimes have a tense aspect?
Almost every couple has both harmonious and tense aspects. A date reaches the top when there are noticeably more of the former. A tense aspect in the best date is marked with the word “Friction.”
What does the part of the day next to a date mean?
This is the partner’s birth time at which the date scores the most points: in those hours the partner’s Moon is best placed in relation to your planets.
What changes without my birth time?
Your Moon is taken for noon, and it travels about 13° in a day, so some of its aspects may drop out or appear. Without a birth time, the Ascendant is not calculated.
How is this different from zodiac sign compatibility?
Zodiac sign compatibility compares only Sun signs. Synastry takes into account the exact positions of several planets, so two people of the same sign may have completely different best dates.