Lunar Mansion Calculator — Your Moon's Manzil (28 Mansions)

What the lunar mansions are

Long before the twelve signs standardized, sky-watchers across Arabia, Persia and India marked the Moon's nightly lodging places. The Moon slides past roughly one star-group a day and returns to its starting point about every 27 to 28 days, so dividing the sky by that walk gives a natural calendar. The Arabic tradition settled on 28 manāzil al-qamar, the stations of the Moon, each with a name, a determinant star and a body of received advice.

Each mansion carries a temperament. The medieval books of election — the Picatrix among them — assign each station a set of undertakings it favors and a set it ruins: journeys here, sowing there, nothing violent while the Moon runs through the Glance. Read as natal coloring, a mansion describes the emotional weather you were born into, in the language of that older world.

To be plain about the epistemics: the mansion is an exact position in the sky, and the position is what this tool computes. The catalog of favorable and unfavorable works is medieval tradition. It is history, not a tested claim, and we present it that way.

How your mansion is computed

Al-Biruni, writing around the year 1000, describes the manāzil as equal divisions and states the convention we follow here: the spans are laid on the tropical zodiac as twenty-eight equal arcs of 12 degrees 51 minutes 26 seconds, beginning at the vernal equinox. Your mansion is then simply the whole-number part of your Moon's tropical longitude divided by that span, plus one.

The Moon's longitude comes from the same modern ephemeris that powers every other tool on this site, so the index is arithmetic over a verified position. The shipped probe checks the table's integrity — twenty-eight contiguous stations — and the boundary behavior at zero degrees Aries, at the end of the first span and at the last degree of the circle.

One honest wrinkle: older sources anchor the mansions to the fixed stars themselves, so their boundaries wander by a degree or two, and the Vedic relatives measure sidereally. Our equal-span convention is stated, consistent and auditable; if a birth Moon sits within a few tenths of a degree of a boundary, neighboring conventions can name the station before or after ours.

What you get back

Cast the chart and the report shows:

• Your mansion's number, Arabic name and English meaning, from Ash-Sharatān, The Two Signs, to Baṭn al-Ḥūt, The Belly of the Fish.
• The determinant star that traditionally opens the station, and the received theme of the mansion for elections and for nativities.
• Your tropical Moon longitude, how deep it sits inside the 12°51′ span, and the mansion's house in your natal chart.

How to read your lunar mansion

Treat the mansion as a month-length filter over the Moon sign. Read the name and meaning first — Al-Buṭayn, the Little Belly, suggests what is hidden and germinating; Az-Zubrah, the Mane, suggests movement and release. Then read the determinant star as the tradition did: the star was the signpost that told you the Moon had arrived, so its own mythology colors the station.

If you work with elections — choosing times for undertakings — track the transiting Moon through the stations and notice which themes the books attach to each. If you read them natally, pair the mansion with the house it occupies in your chart, which localizes the received theme to one theater of life.

A worked example, with real numbers

Take a birth at 17:30 on 1 January 2000 in London. The ephemeris puts the tropical Moon at 226.08 degrees, 16.1 degrees of Scorpio in the fifth house. Divided by the 12.857-degree span, that is mansion 18: Al-Kalb, The Heart, whose determinant star is Antares. The tradition's theme for the station reads: discovery of plots; mixed partnerships. The Moon sits 7.50 degrees into the span, safely mid-mansion.

A second chart, 12:30 on 15 July 1990 in Berlin, gives a tropical Moon at 23.55 degrees — mansion 2, Al-Buṭayn, The Little Belly, determinant Botein, theme of sowing, trade and hidden resources — 10.69 degrees deep in its span, in the sixth house.

A third, 09:00 on 20 March 1988 in Sydney, lands the Moon at 31.14 degrees: mansion 3, Ath-Thurayyā, The Pleiades, determinant Alcyone, counted among the favorable stations for abundance and good outcomes, here falling in the seventh house. Three charts, three stations, one arithmetic.

What the mansions add to a chart

The mansions do not compete with the Moon sign; they subdivide it. Every 30-degree sign holds roughly two and a third stations, so your mansion is a finer address inside the territory the sign already describes. The value is specificity: two Scorpio Moons of the same degree range share a mansion, and the tradition gives them one more descriptive layer in common.

Used well, the mansion is a prompt rather than a verdict. Its medieval catalogs are blunt about trade-offs — almost no station favors everything — and that graininess is more honest than a horoscope that must always be good news.

The 28 mansions against the 27 nakshatras

The Arabic and Vedic lists descend from the same ancient observation and then diverge. The nakshatras number 27, measure the sidereal zodiac, and carry deities and Vimshottari lords; the manāzil number 28, sit on equal tropical spans in the convention we ship, and carry determinant stars and elective themes. Because both track the same Moon, your two station numbers are locked together but not equal — the London example above is mansion 18 and nakshatra 16 at one and the same instant.

If you want both addresses side by side, our Nakshatra Calculator runs the sibling computation over the same birth data, and the two pages state their frames explicitly so the numbers never look like a contradiction.

What this tool does not claim

The mansion is an index over a verified Moon longitude, checked by probe B14, and the equal tropical-span convention is stated rather than pretended to be universal. Star-anchored and sidereal variants exist and shift boundaries by a degree or two.

The names, determinant stars and themes are historical data from the al-Biruni and Picatrix lineage, and no claim is made that any mansion actually favors or ruins any undertaking. The reading is symbolism, labeled as symbolism. Calculations run entirely in your browser. Your birth data is never uploaded, never stored on a server, and never shared.

Our method in one line

Mansion = floor(λ_tropical / 12°51′26″) + 1 over the ephemeris Moon, spans beginning at the vernal equinox after al-Biruni's equal division; houses in Porphyry quadrant houses (whole-sign available on every chart). Reviewed by Dr. Amara Osei, Astronomy Reviewer.