Astrological houses
House Cusp
Direct answer
House Cusp means the boundary or beginning degree of a house in a chosen house system.
A House Cusp is the degree where a house begins.
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At a glance
- In astrology
- In quadrant and equal systems, cusps are degree boundaries.
- Found in
- Houses
- Related
- Birth Chart, Zodiac, Transit
A House Cusp is the degree where a house begins.
A structural orientation; exact placements depend on the chart or technique being discussed.
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What sets House Cusp apart
A cusp is a single degree of the zodiac, the line where one house ends and the next begins, and which degree it falls on depends entirely on the house system. In quadrant systems the Ascendant and Midheaven are fixed by the sky and the other cusps are computed between them. In Whole Sign Houses every cusp sits at 0 degrees of a sign, so the cusp is the sign boundary and the Ascendant degree is only a sensitive point.
- Angles as cusps: cusp 1 is the Ascendant, 4 the IC, 7 the Descendant, 10 the Midheaven
- Equal houses: each cusp 30 degrees after the Ascendant degree
- Whole Sign: each cusp at 0 degrees of a sign
- Placidus: cusps by trisecting time arcs, from Placidus de Titis, 17th century
- Near a cusp: a planet within about 5 degrees before a cusp is often read in the next house, a rule of thumb that varies
Often mistaken for something else: A cusp is a house boundary, not a sign boundary. Someone born "on the cusp" of two Sun signs has a Sun near 0 or 29 degrees of a sign; that has nothing to do with house cusps.
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What a house cusp is
A house cusp is the line where a house begins: the degree of the zodiac that marks its start. In most house systems the cusp of the first house is the Ascendant, the degree rising on the eastern horizon at birth, and the cusp of the tenth is the Midheaven, the highest point of the Sun's path that day.
The sign on a cusp colors the whole house, and the planet that rules that sign is the house's ruler: where that planet sits in the chart shows where the affairs of the house are carried out.
Why cusps move from one house system to another
The cusps depend on the house system. In whole sign houses, the oldest system, each house is simply one sign and every cusp is 0 degrees of a sign. In equal houses each house is exactly 30 degrees, counted from the Ascendant. Placidus, the default in most modern Western software, divides the time the degrees of the zodiac take to rise and culminate, so its houses vary in size.
At high latitudes quadrant houses grow very unequal, and a sign can fall wholly inside one house without touching a cusp, which astrologers call an intercepted sign; above the polar circles Placidus cannot be calculated at all. The same planet can fall in a different house from one system to the next, which is why it is worth knowing which system a chart uses.
A planet on the cusp
A planet within a few degrees before a cusp is often read as belonging to the house that begins there; many astrologers allow about five degrees, and some allow more near the angles. A planet close to the Ascendant, Descendant, Midheaven or IC is especially strong, because the angles are the most sensitive points of the chart.
Born on the cusp: signs, not houses
"Born on the cusp" usually means something else: a birth near the day the Sun changes sign, around the 19th to the 23rd of a month. The Sun is always in one sign or the other, never both, and an exact birth time and place settle which.
The story behind House Cusp
House cusps became central as astrologers developed mathematical house division methods beyond whole signs.
The spiritual meaning of House Cusp
Spiritually, a House Cusp is a doorway: it shows how a life topic is entered.
House Cusp in astrology
In quadrant and equal systems, cusps are degree boundaries. In Whole Sign Houses, sign boundaries define houses while the Ascendant remains a sensitive degree.
Why House Cusp matters
House Cusp matters because it shows which sign and ruler govern a house and where planets may shift topics by house system.
House Cusp in practice: an example
A Tenth House cusp in Capricorn points to Saturn as an important planet for career and public responsibility.
Where readings of House Cusp go wrong
It is a mistake to read a cusp without naming the house system that created it.
Sources and editorial method
This entry summarizes the tradition in the Almanac's own words; where no source is listed, it is an editorial summary rather than a primary text, and symbolic readings are named as the tradition's, not as fact.
- Source
- The Great Almanac Dictionary
- Category
- Houses
- Last updated
- 2026-09-26
Find your house cusps
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Related terms
More in Houses
- Intercepted House
- Placidus
- Planet in the Ninth House
- Porphyry Houses
- Succedent Triad
- Angular Houses
- Derived Houses
- Equal Houses
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Common questions
What is a house cusp?
House Cusp means the boundary or beginning degree of a house in a chosen house system.
Where does a house cusp come from?
House cusps became central as astrologers developed mathematical house division methods beyond whole signs.
What does a house cusp mean in astrology?
In quadrant and equal systems, cusps are degree boundaries. In Whole Sign Houses, sign boundaries define houses while the Ascendant remains a sensitive degree.
What does a house cusp look like in a birth chart?
A Tenth House cusp in Capricorn points to Saturn as an important planet for career and public responsibility.
What does a house cusp mean spiritually?
Spiritually, a House Cusp is a doorway: it shows how a life topic is entered.
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