Koch House System Chart Calculator

Koch cusps come from birthplace time arcs, not ecliptic geometry

The Koch system, sometimes called the "birthplace system," calculates house cusps by dividing the time between a reference point and the moment of birth into arcs tied to your specific birthplace latitude, then converting those arcs into ecliptic degrees. This is a different starting calculation than quadrant systems like Placidus, which divide time along the celestial equator instead.

The practical effect is that Koch cusps can sit at noticeably different degrees than Placidus cusps for the same birth data, especially for houses away from the angles (2nd, 3rd, 5th, 6th, and their opposites).

Koch and Placidus agree closely near the equator, diverge at higher latitudes

For birth locations close to the equator, Koch and Placidus cusps tend to be fairly similar. As birthplace latitude increases, the two systems diverge more, and at high latitudes Koch's time-arc calculation can become unstable or fail outright, inside the polar circle, where the sun doesn't rise or set in the ordinary way for parts of the year, the math the system depends on breaks down.

Equal House and Whole Sign don't have this failure mode at all, since neither depends on time arcs or the local horizon. That's the main reason either is recommended as a fallback for high-latitude births instead of Koch.

Walter Koch and the rise of the birthplace system

Koch houses are named for Walter Koch, a German astrologer who published the system in 1971, building on earlier proposals by other researchers. It gained particular traction in German-language astrology, where it's often used as the default in place of Placidus.

Reach for Koch if you practice in a German-language tradition or want a birthplace-anchored alternative to Placidus

Koch is worth trying if you're working within German-language astrological tradition, where it's frequently the default, or if you specifically want a system anchored to your literal birthplace time rather than an equatorial or ecliptic construction. It's not recommended for high-latitude births, where Equal House is the more reliable fallback.

How Koch compares to Placidus, Campanus, and Regiomontanus

Placidus, Campanus, and Regiomontanus are all quadrant systems, like Koch, meaning they divide the space between your four angles (Ascendant, MC, Descendant, IC) into three houses each rather than using equal 30-degree divisions. But each uses a different reference circle: Placidus divides time along the celestial equator, Campanus divides the prime vertical, and Regiomontanus divides the celestial equator differently than Placidus, Koch is the only one of the four anchored to birthplace time arcs rather than a fixed great circle.