Last updated June 13, 2026
Hellenistic Time Lords
Planetary Years Calculator
Find the lesser, mean, greater, and greatest years of the seven traditional planets, then project them from your birth date so your chart ruler's landmark ages land on real dates.
What are the planetary years?
The planetary years are fixed counts of years that traditional astrology assigns to each of the seven classical planets. Each planet carries four of them: a lesser, a mean, a greater, and a greatest value. They appear in Hellenistic sources such as Vettius Valens and were tabulated by later writers including al-Biruni, who tied each count to a recurring astronomical cycle for that planet.
The lesser years are the figures most often used. Venus is 8, Jupiter 12, Mars 15, the Sun 19, Mercury 20, the Moon 25, and Saturn 30. Those seven numbers add up to 129, which is the same total that builds the decennial periods. The greater years run longer, the mean years are the average of the lesser and greater, and the greatest years are a maximal cycle that sits far beyond any single lifetime.
On their own the year counts are just a reference table. This calculator does the second step that practitioners actually want: it projects those years forward from your birth date so they become real ages and calendar dates, and it weights them by the planets that matter most in your own chart.
How this calculator projects your years
The year counts are the same for everyone. What makes the projection personal is which planet you read them through. The calculator finds your chart ruler, the traditional domicile lord of your Ascendant, and your sect light, the Sun if you were born in the day and the Moon if you were born at night. A landmark of either of those two planets tends to read louder than the same band of a more peripheral planet.
From there it counts each planet's lesser, mean, and greater years forward from your birth date and turns them into dated landmarks. Your chart ruler's three landmarks lead the result, followed by the next landmark you reach across all seven planets and a full timeline of every dated landmark in order. The greatest years are kept in the reference table but not dated, since values like the Sun's 1461 or Venus's 1151 are symbolic cycles, not ages a person lives to see.
Because the chart ruler and sect light both depend on the moment of birth, the projection needs an exact birth time. The year counts do not change, but the planet you key them to can. If your time is uncertain, a birth time rectification pass will tell you whether the Ascendant and sect are landing right.
The four bands, planet by planet
Each planet's lesser years come from its shortest characteristic cycle. Venus returns to the same point against the Sun every 8 years, Jupiter orbits in about 12, and the Sun's 19 matches the Metonic cycle that realigns Sun and Moon. The greater years extend the same idea to a longer return, the mean years average the two, and the greatest years reach for the planet's maximal period.
| Planet | Lesser | Mean | Greater | Greatest |
|---|---|---|---|---|
| Saturn | 30 | 43.5 | 57 | 265 |
| Jupiter | 12 | 45.5 | 79 | 427 |
| Mars | 15 | 40.5 | 66 | 284 |
| Sun | 19 | 69.5 | 120 | 1461 |
| Venus | 8 | 45 | 82 | 1151 |
| Mercury | 20 | 48 | 76 | 480 |
| Moon | 25 | 66.5 | 108 | 520 |
Notice that the mean years are often fractional, like Saturn's 43.5 or the Sun's 69.5. That is because the mean is literally the midpoint between the lesser and greater values, not an independently observed cycle.
Reading one of your landmarks
When you reach the age that equals one of a planet's years, that planet is, in the old image, called to render its account. The topics it governs come up for review. A Saturn landmark asks about structure, duty, and what has been carried too long. A Venus landmark draws attention to bonds, value, and pleasure. The number tells you when to look; the planet's natal condition tells you how the chapter is likely to feel.
Weight the landmarks of your chart ruler and sect light above the rest, and treat each one as a window around the date rather than a single fixed day. The fastest way to trust the technique is to run it backward: look at the landmarks you have already passed and see whether those ages line up with real turning points in your life. That retrospective check is how the tradition argued the method, and it calibrates what a given planet's years tend to mean for you.
Planetary years, length of life, and the period systems
Historically the lesser years anchored the length-of-life doctrine. The hyleg was the chart's vitality point, and the alcocoden was the planet that gave its years to that point. The Sun's greater years of 120 functioned as the symbolic ceiling of a full life. Modern practice rightly treats all of this as symbol rather than prediction, which is the framing this calculator keeps.
The same year counts also build the time-lord systems. The decennials divide equal 129-month decades by the lesser years, and the firdaria hand each planet a multi-year era. Layer either with annual profections, and when the profection lord matches a planetary-year landmark, that planet's testimony stacks for the year.
What each planet's years tend to mean
Every traditional planet carries its own four year counts. Reaching one of a planet's landmark ages tends to call that planet's topics up for review. Read each through the planet's natal condition, not the number alone.
Saturn years
The account of time, endurance, and structure
Saturn's least period is just under 30 years, the length of its orbit, so its first landmark coincides with the Saturn return that ushers in self-authored adulthood. Saturn keeps the account of time itself: structure, duty, boundaries, endurance, and the slow work that compounds. Reaching a Saturn landmark tends to ask what has been built and earned, and what has been carried past its use. Read it through the houses Saturn rules and occupies, the parts of life where maturity, limitation, and long responsibility concentrate.
Lesser 30 · Mean 43.5 · Greater 57 · Greatest 265
Jupiter years
The account of growth, meaning, and increase
Jupiter's least period is about 12 years, one orbit and one full turn of the annual profection wheel, so its landmark falls on the Jupiter return. Jupiter keeps the account of growth and meaning: opportunity, education, faith, patronage, and increase. Reaching a Jupiter landmark tends to surface where you have expanded, what has been promised or invested, and whether that faith has been rewarded or overextended. Judge it by Jupiter's natal condition and the houses it governs rather than expecting reward to arrive on schedule.
Lesser 12 · Mean 45.5 · Greater 79 · Greatest 427
Mars years
The account of effort, conflict, and drive
Mars's least period is 15 years, the span of seven of its synodic cycles, after which Mars returns to roughly the same place against the calendar. Mars keeps the account of effort and conflict: drive, courage, heat, competition, and the cost of exertion. Reaching a Mars landmark tends to mark where energy has been spent and friction has gathered since the last measure, whether that reads as decisive action, strain, or a fight worth picking. The houses Mars rules and occupies show where the heat lands.
Lesser 15 · Mean 40.5 · Greater 66 · Greatest 284
Sun years
The account of purpose, vitality, and recognition
The Sun's least period is 19 years, the Metonic cycle in which 235 lunar months realign Sun and Moon to the same phase and place. The Sun keeps the account of purpose and vitality: identity, direction, recognition, and the integrity of what you set out to become. Reaching a Sun landmark tends to bring that into focus, asking whether your visible life still matches your aim. The Sun's greater years of 120 stood in the tradition as the symbolic ceiling of a complete human life.
Lesser 19 · Mean 69.5 · Greater 120 · Greatest 1461
Venus years
The account of love, value, and connection
Venus's least period is 8 years, the rhythm in which five of its synodic conjunctions with the Sun trace a near-perfect pentagram. Venus keeps the account of love and value: relationship, pleasure, art, money, and what you treasure. Reaching a Venus landmark tends to draw attention to where bonds have deepened, frayed, or asked for repair, and to what has felt worth keeping. The surrounding chart, and Venus's own condition, decide whether those topics arrive as ease or as cost.
Lesser 8 · Mean 45 · Greater 82 · Greatest 1151
Mercury years
The account of skill, exchange, and learning
Mercury's least period is 20 years, after which sixty-three of its quick synodic cycles return it to the same standing against the Sun. Mercury keeps the account of skill and exchange: learning, language, craft, trade, travel, and the handling of information. Reaching a Mercury landmark reads as a checkpoint on what you have learned and traded, the messages sent and the deals made, and on how your chart organizes change. Watch the houses Mercury rules and the planets it touches for the texture.
Lesser 20 · Mean 48 · Greater 76 · Greatest 480
Moon years
The account of body, care, and changing circumstance
The Moon's least period is 25 years, the old luni-solar cycle of about 309 lunar months that Egyptian astronomers used to reconcile Moon and calendar. The Moon keeps the account of body and care: rhythm, nourishment, family, habit, and changing circumstance. Reaching a Moon landmark tends to surface what has been tended and what has shifted in the foundation of a life, the conditions that move underneath everything else. Read it as a lens on changeable circumstance rather than as a health indicator.
Lesser 25 · Mean 66.5 · Greater 108 · Greatest 520
Related Free Tools
Alcocoden Calculator
Find the planet linked to your hyleg's degree and compare traditional planetary-year bands with modern safety framing.
Firdaria Calculator
Calculate your current firdaria period: the planetary era, planetary sub-period when applicable, and transition dates.
Decennials Calculator
Calculate your decennial periods and sub-periods: the planet ruling each 10 year 9 month chapter, the sub-period inside it, and exact transition dates.
Hyleg Calculator
Find the traditional vitality point selected from Sun, Moon, Ascendant, Lot of Fortune, and prenatal syzygy, with visible house and dignity rules.
Frequently Asked Questions
What are the planetary years in astrology?
Planetary years are fixed counts of years assigned to each of the seven traditional planets, preserved in Hellenistic and medieval sources such as Vettius Valens and al-Biruni. Each planet has a lesser, mean, greater, and greatest value. Saturn is 30, 43.5, 57, and 265; Jupiter is 12, 45.5, 79, and 427; Mars is 15, 40.5, 66, and 264; the Sun is 19, 69.5, 120, and 1461; Venus is 8, 45, 82, and 1151; Mercury is 20, 48, 76, and 480; the Moon is 25, 66.5, 108, and 320. They are used for length-of-life work and as a measure for timing techniques.
What is the difference between the lesser, mean, greater, and greatest years?
The lesser years are each planet's shortest characteristic period, drawn from a recurring astronomical cycle: Venus 8, Jupiter 12, Mars 15, the Sun 19, Mercury 20, the Moon 25, and Saturn 30. The greater years are a longer cycle for the same planet. The mean years are simply the average of the lesser and greater values, which is why they are often fractional. The greatest years are the maximal cycle, far longer than any lifetime, so they read as a symbolic ceiling rather than a dated age.
How does this calculator personalize the planetary years?
It projects each planet's lesser, mean, and greater years forward from your birth date, so the year counts become real calendar dates and ages in your own life. It also finds your chart ruler, the traditional domicile lord of your Ascendant, and your sect light, the Sun by day or the Moon by night, because the landmarks of those two planets carry the most personal weight. The greatest years are shown in the reference table but not dated, since they exceed a human lifespan.
Do planetary years predict lifespan or death?
No. Historically the lesser years fed the hyleg and alcocoden length-of-life doctrine, and the Sun's greater years of 120 stood as the symbolic ceiling of a full life, but modern practice should not read any planetary-year date as a literal prediction of death. This tool presents the landmarks as symbolic timing windows to watch the relevant planet, not as a clock. For the specific length-of-life technique, the alcocoden calculator handles that doctrine with the same caution.
Why do the planetary years need my exact birth time?
The year counts themselves are fixed and do not need a birth time. The personalization does. Your chart ruler depends on your Ascendant, which moves about one degree every four minutes, and your sect light depends on whether the Sun was above or below the horizon at birth. Both can change with an uncertain time, especially near a sign boundary on the Ascendant or near sunrise and sunset for sect.
How do planetary years relate to firdaria and decennials?
They are the raw material. The decennials technique builds equal 129-month decades, where 129 is the sum of the seven lesser years, and divides each decade among the planets by those same lesser years. Firdaria hands each planet a multi-year era of its own. Planetary years are the underlying measure; firdaria and decennials are two ways of spending them across a life.
Methodology: The planetary year counts follow the traditional Hellenistic and medieval tables (Valens, al-Biruni). Landmark dates are projected from your birth date using a 365.2425-day year. Your chart ruler is the traditional domicile lord of your Ascendant, and sect is set by whether the Sun was above or below the horizon at the exact birth moment, so approximate birth times cannot reliably fix the chart ruler or sect near a sign boundary or near sunrise and sunset. Read every landmark as symbolic timing testimony, not as a prediction.
Keep your planetary-year landmarks with your chart
Create a free account to save your chart, revisit every landmark age, and read your planetary years alongside live transits and the rest of your time lords.