The twelve houses
| House | Name | Life domain |
|---|---|---|
| 1st | House of Self | Identity, body, presence, the way you arrive in a room |
| 2nd | House of Resources | Money, possessions, values, what you build with |
| 3rd | House of Mind | Communication, siblings, immediate environment, learning |
| 4th | House of Home | Home, family of origin, ancestry, inner foundation |
| 5th | House of Pleasure | Romance, creativity, play, children, self-expression |
| 6th | House of Body | Daily work, health, routine, service, the body's rhythm |
| 7th | House of Partners | Marriage, partnership, contracts, the mirror in the other |
| 8th | House of Depth | Intimacy, shared resources, transformation, the underworld |
| 9th | House of Meaning | Travel, philosophy, higher learning, belief, broad horizons |
| 10th | House of Vocation | Career, public role, authority, what you're known for |
| 11th | House of Community | Friends, networks, futures, collective belonging |
| 12th | House of the Hidden | Solitude, dreams, the unconscious, what's behind the curtain |
To read the houses of your own chart in order, from what a house is to a planet sitting near a cusp, follow houses, step by step. One house has a page of its own so far: the first house, with the Ascendant, each planet in it and the empty first house.
The Placidus system
Placidus is a quadrant-based house system: it splits the diurnal and nocturnal arcs of points on the ecliptic, the time a degree spends between the horizon and the meridian, into three equal parts. This produces twelve unequal houses in which the rising point (Ascendant) and the culminating point (Midheaven) are the cusps of the 1st and 10th respectively.
NatalChart.AI calculates Placidus only, and there is no house-system switch in the product. We chose it because it’s the most widely used system in modern western astrology and matches the convention of professional software (astro.com, TimePassages and others).
The four angles
- Ascendant (1st House cusp): the zodiac degree rising on the eastern horizon at your birth moment. Marks how you arrive.
- IC (4th House cusp): the lowest point of the chart, opposite the Midheaven. Inner foundation, home of origin.
- Descendant (7th House cusp): opposite the Ascendant. The mirror in the other.
- Midheaven / MC (10th House cusp): the highest point of the chart at birth. Public role, vocation.
How NatalChart.AI computes house cusps
- Your birth UTC moment is converted to local sidereal time at the birthplace latitude / longitude.
- The local sidereal time and latitude feed the Placidus algorithm, which returns the twelve cusps.
- Planets are assigned to houses by checking which cusp pair their longitude falls between.
- The same calculation returns the Ascendant, the Midheaven and the Vertex. The Part of Fortune is then ASC + Moon − Sun, for day and night charts alike. Natal aspects are calculated between the 17 bodies, not to the angles.
Why birth time matters so much for houses
The Midheaven moves about one degree every four minutes. The Ascendant moves about as fast on average, but unevenly: depending on the latitude and the sign rising, one sign can cross the horizon in under an hour and another take about three. A fifteen-minute uncertainty in birth time can therefore shift the angles by about 4°, more at some hours, and move planets between houses. The reading marks all house-dependent factors as time-sensitive when the birth time is imprecise.
With no birth time at all the planets are still calculated, and the Ascendant, the Midheaven and the houses are undetermined, not approximate. See how to find your birth time before settling for that.
Frequently asked questions
What are the twelve houses?
The houses are twelve sectors of the chart that map to twelve life areas: self, resources, mind, roots, heart, body, partners, depth, meaning, vocation, community, the hidden. They divide the local sky around your birthplace into twelve unequal regions.
What is the Placidus system?
Placidus is the most widely used house system in modern western astrology. It divides the diurnal and nocturnal arcs of points on the ecliptic, the time each degree spends between the horizon and the meridian, into thirds, producing twelve unequal houses; in this system the Ascendant is the 1st cusp and the Midheaven the 10th. NatalChart.AI calculates every chart in Placidus. There is no house-system switch in the product.
How accurate are the houses if I don't know my exact birth time?
The cusps turn through the whole zodiac every day, at a rate that depends on the place, the date and the sign on the horizon, so there is no universal figure for what a ten-minute error does to your houses. Without an exact time the houses, the Ascendant and the Midheaven are undetermined, not approximate. NatalChart.AI still calculates the planets, for noon as an assumed moment, marks house-dependent factors as time-sensitive and downweights them in the reading. See Unknown Birth Time Natal Chart.
Why do houses matter as much as signs?
A planet's sign describes how it expresses; the house describes where in life it expresses. Mars in Aries says 'forceful, direct'; Mars in Aries in the 6th House says 'forceful and direct in daily work and routines'. The house grounds the placement in real life context.