What Is a House Overlay?
A house overlay is where one person’s planets fall when you place them in the other person’s birth-chart houses. It shows which areas of your partner’s life you touch, and which areas of yours they touch.
A one-sentence definition
Take your planets at their exact zodiac degrees, lay them over your partner’s houses, and note the house each one lands in. That list is your house overlay in their chart. Do the same the other way round and you have their planets in your houses.
Astrologers also call this “planets in partner’s houses” or “synastry house overlays”. The calculator at the top of this page does both directions at once, so you never read only half of it.
Planets say what, houses say where
A planet is a kind of energy: the Moon is feeling and comfort, Venus is affection and taste, Mars is drive and desire. A house is an area of life: home, romance, work, commitment, the things you don’t say. A house overlay pairs the two, so it reads as “this part of you shows up in that part of my life”.
That is why a house overlay feels so specific. Your partner’s Moon in your 4th house is about feeling at home together. The same Moon in your 10th is about how they feel around your ambitions and public life.
Why there are always two directions
Your planets in your partner’s houses and their planets in your houses are two different lists, and they rarely mirror each other. One person can land heavily in the other’s 7th house while the reverse lands in the 11th. Reading both is the whole point: it shows where each of you feels the other.
Whose Birth Time Does a House Overlay Need?
This is the question most calculators get wrong, and it decides which house overlays you can trust. A house overlay needs the birth time of the person who owns the houses. The other person’s birth time barely matters.
Only the house owner’s time decides the houses
House cusps turn with the Earth, about 15 degrees an hour, so they depend on the exact minute of birth. Planets move far more slowly: apart from the Moon, they shift less than a degree in a day. Move the house owner’s time and every cusp, and every house overlay, moves with it. That is why your planets in your partner’s houses depend on your partner’s birth time, not yours.
We measured it on 3,000 random couples. Shifting the house owner’s birth time by one hour changed the house of 50% of the partner’s planets. Shifting the planet owner’s time by the same hour changed 0.21%, more than two hundred times less.
What the planet owner’s time changes: just the Moon
The Moon covers about 13 degrees a day, so it is the one planet whose house can depend on its owner’s birth time. If your partner doesn’t know when they were born, their Moon could sit in either of two of your houses. That happened in 43.6% of our test charts; the other nine planets were unaffected.
So you can read the house overlay of your partner’s planets in your houses with only your own time. The calculator shows the Moon’s two possible houses and the local time it changed house that day.
How close is close enough?
Birth certificates round, and family memories drift. The calculator lets you say how sure each time is and then shows every possible house for each house overlay, with its share of that window, instead of pretending to one answer.
Exact to the minute
Every house overlay is a single house. The flags still tell you which planets sit close enough to a cusp that a few minutes would matter.
Within 15 minutes
Three planets in four (74.2%) stay in one house across the whole window. The rest have two candidates, and you see which is more likely.
Within an hour
Most planets (85.1%) narrow to two neighbouring houses. That is still useful: “7th or 8th” is a real answer, and the shares show which side is heavier.
Unknown
With no time at all, a planet can fall in any of six or more houses over a day, so that direction is shown as unavailable. If you know the morning or the evening, use the two-hour window, or narrow down an unknown birth time with the rising-sign calculator first.
How to Use the House Overlay Calculator
The house overlay calculator works out both directions in three house systems at once, so switching between them is instant. Here is the order we suggest for reading the result.
Step 1: Enter both birth dates and places
Add each person’s birth date, time and place. Names are optional and only label the results.
Step 2: Say how sure you are of each time
Choose Exact, or a window of 15 minutes to 2 hours. Tick “unknown” if there is no time at all: that person’s houses can’t be used, but their planets still can.
If you don’t have your own chart handy, check your own birth chart first: the time you enter there is the one your partner’s planets depend on.
Step 3: Pick a house system
Placidus is the default. Switch to Whole Sign or Equal at any time; the result changes instantly.
Step 4: Read both columns
One column shows Person A’s planets in Person B’s houses, the other shows the reverse. Each row gives the house and a short reading.
Step 5: Check the flags and the emphasis
Flags mark planets near a cusp, planets that would change house if the house owner’s time moved a few minutes, and planets whose house differs under the other system. The emphasis panel shows where each direction’s weight falls.
In the example above, Alex’s Venus sits 1.2° inside Sam’s 8th house: if Sam had been born six minutes later, it would be in the 7th. A flag like that tells you to read both houses.
The 12 Houses in a Relationship
Each house describes an area of the house owner’s life, and a house overlay tells you what the partner brings into it. Below is how each house reads between two people, grouped the traditional way.
Angular houses: what you both notice first
The 1st, 4th, 7th and 10th sit on the chart’s angles, and planets here are hard to miss. They took 33.5% of house overlays in our sample, about the share you would expect by chance.
1st house: how you see yourself around them
Their planet colours your self-image and the way you come across. The effect is immediate, sometimes flattering, sometimes too close.
4th house: home, family, feeling safe
They touch your sense of home and your private self. This placement often feels like family, for better and for worse.
7th house: partnership and commitment
Their planet lands where you look for a partner. It tends to raise the question of commitment, and it also shows where you negotiate.
10th house: ambition and public life
They show up in your goals, your reputation and how the world sees you as a couple. Support here feels like a push forward.
Succedent houses: what you build and keep
The 2nd, 5th, 8th and 11th follow the angles and are about resources and attachment. They held 33.1% of house overlays.
2nd house: what you value and spend
Their planet touches money, possessions and self-worth. It can steady you, or it can become the thing you argue about.
5th house: romance, play, delight
This is the classic romance house: fun, flirting, creativity and children. Personal planets here make time together feel light.
8th house: intimacy and what you share
Their planet reaches the depths: sex, trust, shared money and the things that change you. It is intense, and it asks for honesty.
11th house: friends and shared hopes
They touch your friendships and your plans for the future. This placement often grows out of friendship, or keeps one alive inside a romance.
Cadent houses: what you learn and adjust
The 3rd, 6th, 9th and 12th are houses of learning and adjustment, and took the remaining 33.4% of house overlays. Their effect is quieter but steady.
3rd house: everyday talk and ideas
Their planet lives in your conversations, messages and daily routes. It often shows up as easy talk, or as constant debate.
6th house: routines and care
They become part of your days: habits, health, chores and how you look after each other. It is less glamorous than the 5th, and often lasts.
9th house: beliefs, travel, growth
Their planet widens your view through travel, study and big ideas. It can also mean you disagree about what matters most.
12th house: what stays unspoken
They touch your private inner life, the part you rarely show. This can feel tender and hard to explain, and it can hide things that need saying.
Which House Overlays Matter Most?
Not every house overlay carries the same weight. Here is the order most astrologers read them in, with the numbers that keep it honest.
Start with the personal planets
The personal planets are the Sun, Moon, Mercury, Venus and Mars. The Sun, Moon, Venus and Mars describe the most personal parts of a person, so a house overlay of these planets in a partner’s houses is felt most; Mercury comes next, then Jupiter and Saturn. Uranus, Neptune and Pluto come last, for reasons explained in the next section.
The 5th, 7th and 8th: more common than they feel
People search for these three house overlays more than any others, and they are worth reading. But they are not rare. In our sample of 6,000 couples, 65.1% of people had at least one personal planet in their partner’s 5th, 7th or 8th house.
So having one says little on its own about where the relationship is going. The planet, the house and whether it runs both ways tell you much more than the fact that it exists.
Clusters: three or more planets in one house
When several of your planets land in one of your partner’s houses, that area of their life becomes the centre of the relationship. For 29.1% of the people in our sample, three or more of their five personal planets gathered in one of their partner’s houses; counting the Sun to Saturn, 46.5%.
The emphasis panel shows where each direction’s house overlays are heaviest and names any cluster. In the example couple, Sam’s Sun, Venus and Jupiter all fall in Alex’s 6th house.
Planets sitting on a cusp
About one planet in eight (13.2%) sits within 2° of a house cusp. Read those house overlays as belonging to both houses, and check the time flag: a few minutes of the house owner’s birth time decide which side wins.
Outer Planets in Your Partner’s Houses
Uranus, Neptune and Pluto move so slowly that everyone born within a few years shares them. That changes how much their house overlay says about the two of you.
Why same-age couples share them
If you and your partner were born within five years of each other, their Neptune and Pluto usually land in the same house as your own Neptune and Pluto: 80.8% and 81.2% of the time in our sample, and 62.6% for Uranus. Across all age gaps the figures fall to 22.7%, 23.5% and 12.2%.
In other words, a same-age partner’s outer planets mostly echo where your own already are. The house overlay is real, but it describes your generation more than your relationship.
When outer-planet overlays do matter
Read outer-planet house overlays closely when there is a big age gap, because then they bring something you don’t already have. They also matter when they sit right on your Ascendant, Descendant, Midheaven or IC, or on one of your personal planets.
Placidus or Whole Sign? Why House Overlay Calculators Disagree
If two calculators give you different houses, neither is necessarily wrong. They are probably using different house systems, and the difference is larger than most people expect.
About half the overlays change house
We compared Placidus and Whole Sign houses on 1,500 couples in each of five latitude bands. Between 51.2% and 63.1% of all house overlays changed house, more the further from the equator the house owner was born. In 91.5% to 99.3% of couples at least one planet moved.
Equal houses sit closer to Placidus near the equator (8.3% different) and drift apart further north (48.9% at 55–62°). The example couple is on the high side: 7 of Sam’s 10 planets change house in Alex’s chart.
Houses are not the same size
Whole Sign houses are always 30° wide; Placidus houses are not. Between 25° and 55° north, Placidus houses ranged from 14.0° to 67.5°, and 90% of them were between 19° and 43° wide.
A wide house collects more of your planets when they are laid over your partner’s houses, simply because it covers more of the zodiac. Keep that in mind before reading too much into a crowded house.
Which system should you use?
Placidus is the most widely used system in modern Western astrology and is this site’s default. Whole Sign is the older, Hellenistic approach and is standard in Vedic astrology.
Rather than pick a side, read both. Every row in the calculator shows its Whole Sign house when it differs, and a house overlay both systems agree on is the one to lean on.
Mirror Overlays: When You Light Up the Same House
Sometimes the same planet lands in the same house in both directions. We call that a mirror overlay, and the calculator flags it.
What a mirror overlay is
A mirror house overlay means you each bring the same thing to the same part of the other’s life. In the example couple, Alex’s Sun is in Sam’s 6th house and Sam’s Sun is in Alex’s 6th: both of them come alive in the other’s daily routines.
They are less rare than they sound. In our sample, 52.4% of couples had at least one mirror overlay, and 31.8% had one with a personal planet.
Venus in each other’s 7th house
Venus in a partner’s 7th house is the house overlay people ask about most. In our sample, 16.6% of couples had it in at least one direction. When it runs both ways, each of you sees the other as a natural partner, and that is worth noticing.
Venus overlays also come alive when Venus itself is active in the sky, as during a Venus retrograde.
Who feels an overlay more?
The two people feel a house overlay differently. The house owner usually notices an area of life being lit up, stirred or steadied. The planet owner feels needed, at home or challenged in that area.
Neither feeling is stronger by rule. A personal planet in your partner’s houses registers more than an outer one, on both sides.
House Overlays vs Synastry Aspects vs the Composite Chart
Relationship astrology has three main tools, and each answers a different question. House overlays are one of them, not the whole picture.
Overlays: where the contact lands
A house overlay tells you which area of each person’s life the other touches. It needs the house owner’s birth time and gives you two lists: your planets in your partner’s houses, and theirs in yours.
Aspects: how two planets talk
Synastry aspects are the angles between your planets and your partner’s, such as a trine or a square. They describe how two energies get along, and most of them need no birth time. The full synastry chart shows them all with readings.
Composite: the relationship as its own chart
A composite chart combines the two charts into one by midpoints, and a Davison chart casts a chart for the midpoint in time and space. Both describe the relationship as a third thing, not each person’s experience of the other.
| House overlay | Synastry aspects | Composite chart | |
|---|---|---|---|
| Answers | Where each of you feels the other | How your planets interact | What the relationship is like |
| Birth time needed | The house owner’s | Mostly no | Both, for houses |
| Directions | Two | One shared list | One chart |
| On this site | This page | Synastry chart | Composite and Davison |
House Overlay FAQ
›Do both people need an exact birth time for house overlays?
No. Only the house owner’s birth time matters, because it sets the cusps; the other person’s planets move very little in a few hours. In our test of 3,000 couples, moving the house owner’s time by one hour changed the house of 50% of the planets, while moving the planet owner’s time by an hour changed 0.21%, and only ever the Moon.
›Can I see house overlays without my partner’s birth time?
Yes, in one direction: your partner’s planets in your houses only need your time. The other direction, your planets in your partner’s houses, needs theirs. If only their time is missing, their Moon is the one planet that can land in two houses, which happened in 43.6% of our test charts.
›Who feels a house overlay more, the planet person or the house person?
They feel different things. The house person usually notices an area of life being lit up or stirred; the planet person feels needed or at home in that area. How strong it feels depends mostly on the planet: the Sun, Moon, Venus and Mars register more than Uranus, Neptune or Pluto.
›What are the most important house overlays?
Start with the personal planets (Sun, Moon, Mercury, Venus, Mars), above all the Sun, Moon, Venus and Mars, in the 1st, 4th, 5th, 7th, 8th and 10th houses, then any house holding three or more of the partner’s planets. Planets right on a cusp or angle count for both houses. Because 65.1% of people have at least one personal planet in their partner’s 5th, 7th or 8th house, look at the combination, not at one placement.
›Is it good if my partner’s Venus falls in my 7th house?
It is one of the warmest overlays: their affection lands in the part of your chart about partnership and commitment, and it often feels like an invitation to be a couple. It is not rare (16.6% of couples have Venus in the other’s 7th one way or both) and it does not guarantee anything on its own. Read it with the synastry aspects between your charts.
›What does it mean if many of their planets fall in my 12th house?
The 12th house is about what goes unsaid, so the connection can feel deep, private and hard to put into words, and it can invite idealizing or avoiding hard conversations. It is not a bad sign in itself. Check the flags first: a planet near the 1st-house cusp may belong to your 1st, and Whole Sign can put it there too.
›Should I use Placidus or Whole Sign for house overlays?
Both are legitimate, and they disagree often: across 1,500 couples per latitude band, 51–63% of overlays changed house between them. This calculator uses Placidus by default and flags every row whose house differs under Whole Sign. An overlay both systems agree on is the one to lean on.
›Do house overlays matter more than aspects?
They answer different questions. Aspects describe how two people’s planets interact; house overlays describe where in each life that contact is felt. Read the aspects first for the quality of the bond, then use the overlays to see which areas of life it plays out in.
›Is the house overlay calculator free?
Yes, with no account. Everyone gets both directions, every planet’s house in three house systems, the cusp, time and system flags, the emphasis summary, a short reading for each placement and the full reading for each direction’s strongest overlay. Pro adds the full reading for all twenty placements.
›Can I use house overlays for friends or family?
Yes. The geometry is the same for any two people, and houses like the 3rd (conversation), 4th (family) and 11th (friendship) speak directly to those bonds. The readings here are written for couples, so translate the romantic parts into your own relationship.
Related Tools
Both charts side by side, every aspect between you, with readings.
The midpoint chart of the relationship itself.
The relationship’s own birth chart, cast for the midpoint in time and space.
Your exact Ascendant, or the day’s rising-sign windows without a birth time.
Which planets in your two charts the current Venus retrograde crosses.
Ask one question about the two of you and get an answer from both charts.