Last updated: June 12, 2026
A monomoiria calculator finds the planet that rules a single degree of the zodiac, the finest layer of dignity the Hellenistic astrologers left us. Enter your birth chart to see the degree lord of every placement, or look up any one degree on the Find by Degree tab.
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. You will also see the degree lord called the degree ruler or subruler. They all point at the same thing: the planet that governs the exact degree your placement occupies. Two ancient authors carry the technique. Vettius Valens describes it in the Anthology (second century CE), and Paulus Alexandrinus lays out the tables in his Introductory Matters (378 CE).
How degree rulers are calculated
There are two systems in the sources, 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. Here is each one.
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.
One detail the calculator handles for you: degree counting 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′. Off-by-one mistakes here are the most common reason two people get different degree lords for the same chart, the same one-indexing the degree theory calculator follows.
The triplicity system (sect-dependent)
Paulus gives a second method built from the triplicity rulers rather than the Chaldean cycle. Because every triplicity has a day ruler and a night ruler, this version shifts with sect: two people with the same degree can land on different lords if one is a day birth and the other a night birth. It saw far less use among Greek astrologers, and the surviving tables are read differently by different translators, so this calculator computes the standard sign-based table above rather than asserting a contested second one. 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, coarse to fine. The whole sign is thirty degrees. The decan or face is ten. The twelfth-part is two and a half. The bound or term is an uneven block somewhere between two and eight degrees. Monomoiria is the floor: one degree, the smallest unit the tradition rules.
Paulus arranges his chapters in roughly that order, which tells you how he weighted it. Monomoiria is a minor dignity. It modifies; it does not decide. A planet in its own sign and bound but sitting on a degree ruled by Saturn is not suddenly weak. The degree lord tints the placement, it does not overrule the heavier dignities. Read it last, after you have weighed domicile, exaltation, triplicity, bound, and face. The almuten figuris calculator shows how those 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.
When one planet turns up as the degree lord of several of your placements, pay attention. That repetition is the chart pointing at a theme, and it tends to describe a thread that runs through the affairs of every planet that shares the ruler. 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?
Yes, a minor one. It sits below domicile, exaltation, triplicity, bound, and face in weight. It tints a placement rather than deciding its strength, so read it after the heavier dignities, not 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, a bound rules an uneven block of two to eight degrees, and a monomoiria rules a single degree. Monomoiria is the finest of the layers.
What are the two monomoiria systems?
The sign-based system distributes degrees in descending Chaldean order from each sign's domicile lord. The triplicity system distributes them from the trigon rulers and shifts with sect, giving different lords for day and night births. Paulus Alexandrinus records both; the sign-based table is the one in common use, and the one this calculator computes.
Who created the monomoiria system?
No single author. It reaches us through Vettius Valens in the second century and Paulus Alexandrinus in 378 CE, who preserved the tables. Both drew on an older Hellenistic 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.