Ophiuchus 13-Sign Birth Chart Calculator

This calculator uses the 13-sign zodiac based on the visible constellations in the sky.

The 13-sign zodiac recognizes Ophiuchus as the 13th zodiac sign, located between Scorpio and Sagittarius. Unlike the traditional 12-sign zodiac with equal 30-degree divisions, this calculator uses the actual size and position of the constellations as they appear in the sky. It is essentially a planetarium in astrology chart form. New to true sidereal astrology?

For more features including saving charts, transit charts, synastry charts, and more settings please use True Sky online astrology software.