What this calculator tells you
Astrological houses divide a chart using the birth instant and location. Enter those details to see twelve cusp positions and each traditional planet’s house. Choose among eight supported systems; a house number always belongs to the method used to calculate it.
Choose a house system deliberately
The form supports Alcabitius, Placidus, Koch, Porphyry, Regiomontanus, Campanus, whole sign and equal houses. These are different divisions, not interchangeable names for one table. The selected method appears beside every result.
Whole sign starts House 1 at 0° of the rising sign and assigns one sign to each house. Equal houses begin at the actual Ascendant and advance in 30° steps. Quadrant and time-based systems use different geometric constructions, so cusp spacing is often unequal.
How the tool assigns a planet to a house
This implementation assigns house placement by a planet’s ecliptic longitude between consecutive cusps, including the wrap from 360° to 0°. That is the stated placement rule, not a claim to implement every traditional definition of a planet’s spatial house position.
At extreme latitudes some methods cannot supply a valid partition. The tool reports an error instead of substituting another system. Choose another supported method explicitly, and keep its name attached to the new result.
A CONCRETE EXAMPLE
Whole sign and equal houses from the same Ascendant
Take the fixed example’s Ascendant of 24°16′ Aries. Whole sign House 1 starts at 0° Aries and House 2 at 0° Taurus. Equal House 1 starts at 24°16′ Aries and House 2 at 24°16′ Taurus. These follow the two definitions; use the form to calculate their complete tables.
The preserved original uses Alcabitius, where its Sun is in House 10 and Mercury in House 9 despite both being in Capricorn. A sign boundary and a house boundary are different divisions.
This preserved, fictional example uses 1 January 2000, 12:00 UTC, Greenwich (51.4779° N, 0°), tropical zodiac and Alcabitius houses. Its stored source is Swiss Ephemeris 2.10.03. New calculations use Skyfield + JPL DE440; the historical example is not relabelled as a new calculation.
Read it in your own chart.
Keep the date, recorded time, location and zodiac visible as you compare results. Guest calculations need no account.
Use the calculator aboveCommon questions
Which house system is the correct one?
This tool implements eight stated methods. It does not establish that one interpretive tradition is uniquely correct. Choose the method you intend to use, and compare results under matched settings.
Can I calculate houses without an accurate birth time?
The tool requires a time because house orientation changes with time and place. A guessed time can generate numbers but does not establish the person’s actual houses.
Why is one of my houses empty?
A house can contain none of the seven displayed traditional bodies. Empty here describes that body selection; it does not establish that a life area is absent or unimportant.
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.
- Skyfield: positions and coordinates
- NASA/JPL: planetary and lunar ephemerides
- IANA: time zone database