Start at the beginning of the rising sign
The calculation takes the Ascendant’s longitude, divides it by 30°, keeps the completed number of signs and multiplies by 30°. That gives the first boundary. Each following boundary adds another 30°, wrapping after 360°.
This makes sign-to-house counting straightforward. It does not remove the need for birth time and place: a different rising sign shifts all twelve house assignments. Uncertainty close to a rising-sign change deserves particular attention.
The Midheaven remains an independent angle
The tenth whole sign house is the tenth sign counted from the rising sign. Its beginning is not a replacement for the astronomical MC. Read the actual MC degree separately; its location need not be inside the tenth whole sign house.
Check the selected zodiac
Whole sign can be used with the supported tropical or sidereal zodiac. Changing zodiac can change which sign contains the Ascendant. Compare zodiac and, for sidereal charts, ayanamsa before deciding two house calculations disagree.
A CONCRETE EXAMPLE
Worked comparison: Scorpio 3° can change houses
For ARMC 100°, latitude 40° N and obliquity 23.4393°, the geometry calculation gives an Ascendant of 187.988849°, or Libra 7.988849°. Whole sign boundaries begin at 180° for house one, 210° for house two and 240° for house three.
An illustrative planet at Scorpio 3°, longitude 213°, is therefore in house two. Equal houses instead start at the Ascendant degree, putting their second cusp at 217.988849°; that same planet is in house one. Neither calculation moved the planet. In this example, the whole sign tenth begins at Cancer 0°, while the true MC is Cancer 9.189513°.
Read it in your own chart.
Keep the date, recorded time, location and zodiac visible as you compare results. Guest calculations need no account.
Create your free chartCommon questions
Are whole sign and equal houses identical?
Only when the Ascendant lies exactly at the beginning of its sign. Otherwise both use 30° houses but start from different longitudes.
Can whole sign handle every birth location?
It avoids the Placidus semiarc restriction, but still needs a defined Ascendant. Geographic poles and geometrically degenerate inputs are not supported; an error is not replaced by a guessed rising sign.
Calculation & interpretation
New personal calculations use Skyfield with JPL DE440 data and the site’s documented house and zodiac rules. The preserved Greenwich teaching chart has its own historical source label. Worked arithmetic and geometry examples are labelled separately. Astrological meanings are symbolic conventions, not established scientific predictions.
Birth time and place affect angles and houses. Unsupported or ambiguous inputs return an error rather than an invented chart. Personal results stay in browser state and do not create public result URLs.
Read the calculation settings guide