Synastry House Overlays: Placing a Partner's Planets in Your Houses

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A house overlay places one person's planets inside the other person's natal houses. If your partner's Venus falls in your 4th house, astrologers say their Venus "overlays" your 4th, and they read it as a hint about where in your life you may notice what Venus describes in them. The planet says what is involved, its sign says how it tends to express itself, and the house, taken from the other chart, says where in the house owner's life the meeting is often felt. It is a way of asking questions about a relationship, not a way of predicting one.

Educational guide: Astrologist.com does not currently calculate synastry, inter-chart aspects, house overlays or composite charts. The compatibility tool provides a sign-level estimate based on the Sun, Moon and Rising signs; known birth times are required for that tool. The contacts discussed here must be identified separately from the two charts' actual positions.

House overlays are one of the layers listed in synastry basics. Inter-chart aspects compare planet with planet; overlays compare planet with house. The two layers are checked separately and neither replaces the other.

What you need

• The house owner's twelve cusp longitudes. These come from the house owner's birth date, a reliable birth time and the birthplace. The free birth chart draws the cusp lines on its wheel but does not print the cusp degrees, so take the twelve numbers from a source that lists them, matched to the same data and settings. How to find your house cusps sets out exactly what to match: Tropical zodiac, Placidus houses (Equal houses from the Ascendant for births above 66° north or south, as the free chart discloses), time zone and displayed precision. Never read a cusp off the wheel by eye.
• The visiting person's planet positions. The planet table under the free chart gives each planet's sign, degree and minute. The visiting person's birth time is not always needed for these, because most planets move slowly. House overlays and birth time shows when it is and how to check a whole birth date instead.
• Both people's consent. Birth data is personal; compare charts with the agreement of the people involved.

Two directions, two separate questions

A couple has two complete sets of overlays. Person B's planets in person A's houses is one set: it uses A's cusps, so it needs A's reliable birth time. Person A's planets in person B's houses is the other set: it uses B's cusps and needs B's time. The two sets are not mirror images, and one does not tell you anything about the other. Your Sun in my 7th house does not put my Sun in your 7th.

Keep the two lists apart on paper and label them by whose houses they use. Mixing them is the most common way overlays get misread.

The method in four steps

1. Turn each visiting planet into a longitude. Add the start of its sign to its degree and minutes: Aries 0°, Taurus 30°, Gemini 60° and so on to Pisces 330°. So 9°46' Aquarius is 300 + 9 + 46/60 = 309.77°, which a source with more decimals may give as 309.78°.
2. List the house owner's cusps with their widths. Each house runs from its own cusp forward to the next one. The width is the next cusp minus this cusp, plus 360° if the result is negative.
3. Place each planet. Work out how far the planet is past a cusp, counting forward: planet minus cusp, plus 360° if negative. If that distance is less than the house's width, the planet is in that house. A planet exactly on a cusp belongs to the house that starts there; a planet a hair short of the next cusp is still in the earlier house.
4. Mark anything too close to call. If a planet and a cusp show the same degree and minute at the precision you have, display rounding cannot settle which side it is on. Go back to a more precise source or report the placement as borderline.

No margin is added before a cusp in these guides. Some astrologers start reading a planet as part of the next house a few degrees early; that is one practice among several, and the examples here use the cusp itself.

Worked example: Bram's planets in Lotte's houses

Lotte and Bram are fictional. Both charts were calculated with the routines behind the free chart, in the Tropical zodiac with Placidus houses.

• Lotte: 27 August 1991, 06:55, Utrecht (52.0907° N, 5.1214° E), summer time UTC+2. Her full cusp table is worked through on how to find your house cusps: 1st 154.74°, 2nd 175.08°, 3rd 201.77°, 4th 236.13°, 5th 274.62°, 6th 308.09°, 7th 334.74°, 8th 355.08°, 9th 21.77°, 10th 56.13°, 11th 94.62°, 12th 128.09°.
• Bram: 24 March 1990, 21:10, Rotterdam (51.9225° N, 4.4792° E). The Netherlands was still on standard time, UTC+1; summer time began the next day.

The Sun shows why the wrap matters. Lotte's 8th house starts at 355.08° and is 26.69° wide, so it runs from 25°04' Pisces across 0° Aries to 21°46' Aries. Bram's Sun at 3.93° minus 355.08° gives −351.15°; add 360° and the Sun is 8.85° past the cusp, well inside 26.69°. Plain subtraction without the wrap would have suggested the Sun was nowhere near that house.

Two placements sit close to a cusp without being borderline. Bram's Mars is 1.69° past Lotte's 6th cusp and his Jupiter 2.55° short of her 11th. At the 0.01° precision used here both are clearly placed. Whether they would stay put if Lotte's recorded birth time were a few minutes out is a separate question, answered on the birth-time page.

The reverse direction: Lotte's planets in Bram's houses

Now Bram is the house owner and his reliable birth time is the one that matters. His cusps, from the same calculation: 1st 207.28° (27°16' Libra), 2nd 234.19°, 3rd 268.00°, 4th 306.63°, 5th 340.77°, 6th 7.18°, 7th 27.28°, 8th 54.19°, 9th 88.00°, 10th 126.63°, 11th 160.77°, 12th 187.18°. His 5th house runs from 10°46' Pisces across 0° Aries to 7°10' Aries.

Compare the two lists. Bram's Sun falls in Lotte's 8th; Lotte's Sun falls in Bram's 10th. Four of Lotte's planets gather in Bram's 10th, while Bram's planets spread over six of Lotte's houses. A retrograde marker changes nothing in the arithmetic: a planet is placed by its longitude, whichever way it was moving.

Overlays shared by a generation

Bram's Uranus and Neptune land in Lotte's 5th house, which is also where her own Uranus and Neptune sit. That is not a personal link. People born a year or two apart have nearly the same Uranus, Neptune and Pluto, so anyone born around 1990 would put those planets in roughly the same part of Lotte's chart. Astrologers usually read slow-planet overlays as background and give the personal planets and Saturn more attention; Saturn house overlays shows how even Saturn is shared by people born months apart.

Reading an overlay

The house adds a setting to the visiting planet's meaning. Astrologers often associate the houses with these areas of life:

• 1st: self-presentation and first impressions. 2nd: money, possessions and self-worth. 3rd: conversation, learning and the local world.
• 4th: home, family and private foundations. 5th: play, creativity and romance. 6th: routines, work habits and care of the body.
• 7th: one-to-one partnership. 8th: trust, intimacy and shared resources. 9th: beliefs, study and travel.
• 10th: work, direction and public role. 11th: friends, groups and hopes. 12th: rest, retreat and what goes unspoken.

So Bram's Sun in Lotte's 8th might be read as his sense of purpose touching her questions of trust and what is shared, and Lotte's Sun in Bram's 10th as her presence touching his sense of direction. Those are prompts for conversation. They do not say who will do what, they do not show that either person causes anything in the other's life, and the house owner may notice little of it at all.

A few habits keep the reading honest:

• Name the direction every time: "Bram's Sun in Lotte's 8th", not "their Sun-8th overlay".
• Look for repetition, such as several planets in one house, before giving any single overlay weight.
• Check the house owner's own chart first. A house that already holds the owner's planets, or whose cusp ruler is emphasised, gives the overlay a context.
• No score, no verdict. A 7th-house overlay is not a sign of marriage and a 12th-house overlay is not a sign of secrets. Nothing here identifies a soulmate.

The planet guides take this further: Sun and Moon house overlays and Venus and Mars house overlays.

Next steps

Get both people's planet positions from the free birth chart, take each house owner's twelve cusps through the cusp workflow, and fill in one table per direction. Inter-chart aspects are measured separately, as in comparing two charts by degree. The compatibility tool is a different, sign-level estimate from the Sun, Moon and Rising signs and does not look at overlays. Ask the Astrologist can talk through the houses of a natal chart calculated on this site, one chart at a time.

Related articles

• Synastry Basics
• House Overlays and Birth Time
• How to Find Your House Cusps
• House Meanings in Astrology
• House Rulers Explained
• All compatibility guides