About this tool
Zodiac Compatibility Calculator is a free, in-browser toy that takes two birth dates, works out each person's Western sun sign, and gives a light-hearted compatibility score. Nothing is uploaded — both dates are turned into signs and a percentage entirely on your device as you type.
Each sun sign is read from the standard tropical date ranges (for example Gemini is May 21 to June 20). Every sign belongs to one of four elements — Fire (Aries, Leo, Sagittarius), Earth (Taurus, Virgo, Capricorn), Air (Gemini, Libra, Aquarius) and Water (Cancer, Scorpio, Pisces). The score follows a simple fixed rule: the same sign scores 85, two signs of the same element score 90, complementary element pairs (Fire and Air, or Earth and Water) score 80, neutral pairs (Fire and Earth, or Air and Water) score 65, and clashing pairs (Fire and Water, or Earth and Air) score 55.
This is strictly for entertainment. Astrology is not science, and a percentage from date arithmetic says nothing real about a relationship — treat it as a bit of fun to share, not advice. Enter two dates and the signs, elements, score and a playful blurb update instantly.