Why do whole-sign, equal, and Placidus houses disagree?
They apply different geometric or assignment conventions. Whole-sign houses use complete zodiac signs from the ascendant sign, equal houses divide from a chosen starting degree, and Placidus uses a time-based quadrant construction with latitude limits. Their outputs are not interchangeable labels for one calculation.
Direct answer
They apply different geometric or assignment conventions. Whole-sign houses use complete zodiac signs from the ascendant sign, equal houses divide from a chosen starting degree, and Placidus uses a time-based quadrant construction with latitude limits. Their outputs are not interchangeable labels for one calculation.
Practical use
What to do with this answer
Declare the house system, frame, observer, and fallback policy before interpretation. At polar latitudes or near cusps, report unavailable or unstable results rather than silently switching systems.
Distinctions to preserve
- Sign assignment versus equal arcs versus quadrant construction
- Requested method versus silent fallback
- House geometry versus interpretive rule
Limitations
- This answer does not establish that one house system predicts better.
- Some systems can be undefined or unstable at extreme latitudes.
Authority graph
Which existing contracts carry the answer
These linked pages carry the underlying definition, method, or tradition record and its own sources. This page preserves their boundaries rather than becoming a new source of independent authority.
Whole-sign house assignment →
Establishes: Whole-sign houses divide the zodiac into twelve sign sectors; the sign containing the ascendant becomes the first house regardless of ascendant degree.
Boundary: Whole-sign simplicity does not prove the associated house interpretations.
Equal-house convention →
Establishes: Equal houses place the first-house cusp at a selected anchor—commonly the ascendant degree—and add 30° for each subsequent cusp.
Boundary: Equal-house output should not be blended with whole-sign rules without a declared rule-pack dependency.
Placidus house convention →
Establishes: Placidus is a time-proportional quadrant system whose intermediate cusps are derived from diurnal motion between angular positions.
Boundary: Placidus and whole-sign charts must be evaluated as separate declared models, not averaged.
Ascendant labels and whole-sign house geometry →
Establishes: The eastern intersection of the ecliptic and local horizon is one geometric direction for the declared instant, observer, and Earth-orientation convention.
Boundary: Do not combine a tropical ascendant with sidereal planetary signs or borrow house rulers across frames unless an explicitly named tradition rule requires that combination.
Equivalent questions
These query forms resolve to this same answer identity; they are not separate claims.
- Why are my houses different in different apps?
- What is whole sign versus Placidus?
- Can Placidus fail near the poles?
- Should software switch house systems automatically?
Non-claim
This answer is a method or tradition description. It is not a personalized reading and does not certify predictive validity, causation, medical outcomes, legal status, investment value, or guaranteed events.