Last updated: September 18, 2026
What is monomoiria?
Monomoiria is the Hellenistic practice of assigning one planetary ruler to each of the 360 single degrees of the zodiac. From the Greek mono (single) and moira (degree or lot), each degree carries a degree lord that adds a thin layer of essential dignity to any planet placed there. A planet does not only sit in a sign, a bound, and a decan. It also sits in one specific degree, and that degree has an owner.
The plural is monomoiriai, and you will also see the degree lord called the degree ruler. Both name the same thing: the planet that governs the exact degree your placement occupies. Vettius Valens gives the rule in a single sentence of the Anthology (second century CE), where he uses it to pick the first time lord of a 28-year sequence he credits to the earlier astrologer Critodemus. Paulus Alexandrinus is the one who prints the tables, in his Introductory Matters (378 CE). Neither invented it: the deluxe horoscopes on papyrus from Roman Egypt already record a placement's monomoiria next to its sign, bound, and decan.
How degree rulers are calculated
Paulus records two systems, and they do not agree. Some sites quote one and some the other without saying which, so you can get two different answers for the same degree. Surviving charts on papyrus carry a few degree lords that match neither table, so the tradition ran wider than the two canons that reached us. Here are the two Paulus preserved.
The sign-based system (descending Chaldean order)
This is the well-attested table, and the one this calculator computes. The rule has two parts. First, the opening degree of every sign goes to that sign's domicile lord: Aries opens with Mars, Taurus with Venus, Gemini with Mercury, around the wheel. Second, from there you walk the remaining degrees in Chaldean order (Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon), one planet per degree, cycling every seven until all thirty are filled.
Aries is the clean example. Its first degree is Mars, the second the Sun, the third Venus, the fourth Mercury, the fifth the Moon, the sixth Saturn, the seventh Jupiter. Then the eighth degree is Mars again, and the pattern repeats. Taurus starts in a different place because Venus opens it: first degree Venus, then Mercury, Moon, Saturn, Jupiter, Mars, Sun, and around again.
Paulus prints this as a canon of seven columns rather than twelve, one column per domicile lord, so the two signs a planet rules share a single degree sequence. Aries and Scorpio run the same thirty degrees, as do Taurus and Libra, Gemini and Virgo, Sagittarius and Pisces, and Capricorn and Aquarius. Cancer and Leo get a column each, since the Moon and the Sun rule one sign apiece. Thirty degrees is not a whole number of seven-planet cycles, so a sign ends part-way through the order and the next one starts again from its own lord.
One detail the calculator handles for you: degree counting in these tables is ordinal. A planet at 14°50′ Taurus sits in the fifteenth degree, not the fourteenth, because the first degree runs from 0°00′ to 0°59′. The ancient sources already write positions this way, so Valens writing “Libra 6” means what a modern ephemeris prints as 5° Libra. Converting runs the other direction: a modern 6° sits in the seventh degree. Counting from zero is the reason two people read the same chart and come away with different degree lords.
The triplicity system (sect-dependent)
Paulus gives a second method in chapter 32, built from the triplicity rulers rather than the Chaldean cycle. It still runs one planet per degree, cycling seven, but it starts from the triplicity's lord by sect, so two people with the same degree can land on different lords if one is a day birth and the other a night birth. It also had a narrower job than the sign-based table: Paulus credits it to the Egyptian sages and recommends it for pinning down the degree of the Ascendant. Its tables came down corrupt, with the manuscripts disagreeing and one diurnal table putting the Moon where Venus belongs, so this calculator computes the sign-based canon above rather than asserting a reconstruction. If you want the trigon lords that feed the triplicity method, the triplicity ruler calculator shows them directly.
Where monomoiria sits in the dignity stack
Think of the zodiac at five resolutions. The whole sign is thirty degrees. The decan or face is ten. The bound or term is an uneven block running from two degrees up to twelve, so it straddles the decan rather than nesting inside it. The twelfth-part is two and a half. Monomoiria is the floor: one degree, the smallest unit the tradition assigns a ruler to. For what the whole degree number itself is said to carry, separate from its lord, see the degree theory calculator.
Paulus takes the subdivisions in order, signs then bounds then faces then monomoiria, and attaches no weighting to any of them. No ancient or medieval scoring table gives the degree lord a point value: the familiar five-point ladder of domicile, exaltation, triplicity, bound, and face stops before it. Later scholarship treats it as a minor dignity on that basis. Holden groups it with the subdivisions ranked below the terms, and Brennan sets it aside as having seen narrower use than the decans, bounds, and twelfth-parts. Read it as a tint. A planet in its own sign and bound but sitting on a degree ruled by Saturn is not suddenly weak, and the degree lord modifies a placement rather than deciding it. The almuten figuris calculator shows how the heavier dignities stack into an overall winner; monomoiria is the fine print underneath.
What each planet means as your degree ruler
The degree lord lends its nature to the planet that sits on the degree. Read these as tendencies, weighed against the rest of the chart, never as verdicts.
Sun as degree lord
Brought into the light
Moon as degree lord
Responsive and changeable
Mercury as degree lord
Quickened and connected
Venus as degree lord
Softened and sweetened
Mars as degree lord
Sharpened and heated
Jupiter as degree lord
Opened outward
Saturn as degree lord
Weighted and slowed
How to read your monomoiria in a chart
The technique is a two-step lookup, and it is where the degree lord earns its keep. Find the degree lord of the placement you care about. Then go look at where that ruling planet actually lives in your chart, by sign, by house, by its own dignity and aspects. The degree lord does not act in a vacuum; it acts from wherever it sits.
Say your Venus falls on a degree ruled by Saturn. Now find Saturn. If your Saturn is strong and well placed, that Saturnian degree lord lends Venus structure and staying power. If your Saturn is buried in the twelfth and afflicted, the same degree lord reads more like a drag on Venus's affairs. Same degree ruler, opposite flavor, decided by the condition of the ruling planet. The scholiast on Paulus states the judgment directly: a planet on a degree it rules reads well, better still when that degree lord occupies the places of the benefics, and the other way around when the lord is badly placed.
When one planet turns up as the degree lord of several of your placements, that repetition is worth reading as a theme, a thread running through the affairs of every planet that shares the ruler. The same commentary gives it a stronger warrant than pattern spotting: it treats a shared monomoiria as a sympathy between signs that make no aspect at all, so two planets sitting on degrees ruled by the same planet are connected even when nothing else joins them, at least while the contact is applying. If you want the same logic applied to the whole chart rather than one degree, the chart ruler calculator does it for the Ascendant.
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Frequently Asked Questions
What does monomoiria mean?
It is a Greek word, mono (single) plus moira (degree or lot), meaning the rulership of a single degree. In practice it names the system that assigns one planetary ruler to each of the 360 degrees of the zodiac.
How do you calculate monomoiria?
In the standard sign-based system, the first degree of a sign goes to that sign's domicile lord, then the remaining degrees follow the descending Chaldean order (Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon), one per degree, until the sign is full. Find which degree your planet occupies, counting ordinally so 0°00′ to 0°59′ is the first degree, then read off the lord. This calculator does that for every placement.
Is monomoiria an essential dignity?
It is a rulership of a zodiacal subdivision, and Paulus sets it out alongside the bounds and faces. No ancient or medieval scoring table gives it a point value, though: the familiar ladder of domicile, exaltation, triplicity, bound, and face stops before it, which is why modern scholarship treats it as a minor dignity. Read it as a tint on a placement, after the heavier dignities rather than instead of them.
What is the difference between monomoiria and bounds or decans?
They are different resolutions of the same idea. A decan rules ten degrees, an Egyptian bound rules an uneven block running from two degrees up to twelve, and a monomoiria rules a single degree. Monomoiria is the finest of the layers.
What are the two monomoiria systems?
Paulus Alexandrinus records two. The sign-based system in his chapter 5 distributes degrees in descending Chaldean order from each sign's domicile lord. The trigonal system in chapter 32 distributes them from the triplicity rulers and shifts with sect, giving different lords for day and night births. The sign-based table is the one Valens also gives and the one this calculator computes; the trigonal tables came down corrupt in the manuscripts.
Who created the monomoiria system?
No single author. Vettius Valens gives the rule in the second century inside a time-lord chapter he credits to the earlier astrologer Critodemus, and Paulus Alexandrinus prints the tables in 378 CE. Horoscopes on papyrus from Roman Egypt already record degree lords, so both were passing on an older tradition rather than inventing it.
Follow your degree lords as they activate over the years
Save this chart to a free Augurine account, watch your monomoiria lords light up by profection and transit, and trace their condition across the Astro Replay timeline.