Love compatibility by birth date
Enter two birth dates and you get a compatibility score out of 100, free and with no sign-up, along with each person's Sun, Moon, Venus and Mars signs and how far apart they sit. A birth date gives far more than a Sun sign, because the Moon and Venus move on their own schedules.
What a birth date tells you, beyond the Sun sign
Every Leo shares a Sun sign, but they don't share a Moon. The Sun sign comes from the month and the day. The Moon moves through all twelve signs in about 27 days, so two people with the same Sun sign born a week apart usually have different Moons. Venus and Mars move at their own pace too, and they can sit a sign or two from the Sun.
That's why sign-against-sign compatibility calls every Leo and Scorpio the same couple, and two birth dates don't. Astrologers read the Sun as how you move through the world, the Moon as what you need to feel at home, and Venus and Mars as what you're drawn to and how you go after it.
What each pairing reads
The Suns show how two people get along day to day: your pace, your temperament and what each of you takes for granted. The Moons are the private side, and astrologers often read them as the pairing that matters most over years, because they show whether you can rest around each other.
Venus and Mars are the spark. One person's Venus and the other's Mars show who draws whom, and we read them both ways round, because attraction isn't always mutual in the same way. The distance between two signs on the zodiac wheel gives each pairing its tone: the same sign, a sextile, a square, a trine or an opposition.
A worked example
Take two people born on March 2, 1994 and August 20, 1992. Here is what those dates give.
75/100: A strong pairing. Your strongest of the four: Give and take.
| Planet | First | Second |
|---|---|---|
| Sun | Pisces | Leo |
| Moon | Scorpio | Taurus |
| Venus | Pisces | Virgo |
| Mars | Aquarius | Gemini |
- Your Suns: Pisces and Leo. Five signs apart, 150° (a quincunx). This takes some adjusting, because you don't read each other by default.
- Your Moons: Scorpio and Taurus. Opposite signs, 180° apart. You're drawn together and you balance each other, each with what the other is missing.
- Your Venus and their Mars: Pisces and Gemini. Three signs apart, 90° (a square). You push each other here, and tradition reads that friction as what keeps you both moving.
- Your Mars and their Venus: Aquarius and Virgo. Five signs apart, 150° (a quincunx). This takes some adjusting, because you don't read each other by default.
How the score is made
The score is the same one our love calculator gives from two birthdays, and the same one the full compatibility report opens with. It averages four rules: two from your Sun signs, by element and mode, and two from the Moon on both birthdays. The same two dates give the same number whichever is typed first. Each score falls into a band:
- 80 to 100: A natural pairing
- 73 to 79: A strong pairing
- 66 to 72: A pairing that grows with care
- 0 to 65: A pairing that takes work
How the signs are worked out
We take the Moon, Venus and Mars from astronomy-engine, the open-source astronomy library behind our birth charts, at noon UTC on each birthday, and the Sun sign from the date. The signs are the tropical zodiac's. A birth time and place would add the rising sign and houses, which our birth chart calculator works out. How we calculate the sky shows the checks, with tables you can repeat them against.