Gemini and Sagittarius are an extremely compatible match. Gemini is a mutable air sign, and Sagittarius is a mutable fire sign, making this a fiery, passionate relationship. These two signs are opposite one another in the Zodiac, which leads to everything being either wonderful or terrible, but never in between.
Gemini's ideal match is Libra, a fellow air sign, but is also compatible with Aries, Leo, Sagittarius and Aquarius. Sagittarius shares the same compatibility matches as Gemini; however, the ideal match for Sagittarius is Aries, which is also a fire sign. The worst match for Gemini is Capricorn, and the worst match for Sagittarius is Taurus.