Comparison
Placidus vs Whole Sign
Two of the most used house systems in astrology, side by side - with the math, the history, and when each one is right.
| Aspect | Placidus | Whole Sign |
|---|---|---|
| Origin | 17th c., Placidus de Titis (Italy) | Hellenistic (~2nd c. BCE), used across Vedic astrology today |
| Division method | Divides day/night arc by time | One sign = one house; ASC sign = 1st house |
| Cusps | Uneven cusps at 12 different degrees | Cusps always at 0° of each sign |
| Breaks at high latitudes | Yes (>~66°) | No - works anywhere on Earth |
| Best for | Modern psychological / predictive Western astrology | Traditional, Hellenistic, Vedic |
| Used by Astreya for | Western natal chart | Vedic (Jyotish) chart |
How the two systems differ in practice
Take a planet at 28° Aries with an Ascendant at 2° Taurus. Under Whole Sign the planet sits in the 12th house (Aries = the sign before the ASC sign). Under Placidus that same planet might land in the 12th - or the 1st, depending on latitude and time of birth. Neither is a mistake; they use different geometries. Modern Western astrologers usually stay with Placidus for predictive work; traditional and Vedic astrologers use Whole Sign because it maps cleanly onto sign-based rulerships.
FAQ
Which house system does Astreya use?
Placidus for Western natal charts (industry standard), Whole Sign for Vedic charts (traditional Jyotish standard). Both are documented and consistent for every user.
Why do my houses differ between apps?
Because different apps default to different systems. A planet at 28° Aries can sit in the 12th house under Placidus and the 1st under Whole Sign - same sky, different geometry.
Is Placidus more accurate than Whole Sign?
Neither is 'more accurate' - they answer different questions. Placidus divides the diurnal arc by time (best at mid-latitudes for psychological astrology). Whole Sign is the oldest documented system and aligns cleanly with sign-based interpretation.
Does Placidus break at high latitudes?
Yes - above ~66° latitude the math becomes unstable because the ecliptic doesn't rise/set cleanly. For Arctic/Antarctic births astrologers switch to Whole Sign, Porphyry or Equal House.
Can I see both in Astreya?
Your Western chart uses Placidus and your Vedic chart uses Whole Sign - so you already see both perspectives on the same birth data.