Decennials Calculator

Decennials are a Hellenistic time-lord technique that splits a life into seven periods of ten years and nine months, 129 months each, one for each of the traditional planets. The periods begin from the sect light, the Sun in a day chart or the Moon in a night chart, and each one breaks down into seven planetary sub-periods. Seven full periods cover about 75 years, then the cycle starts over.

That 129 comes from somewhere specific. Add the lesser years of the seven planets, Saturn 30, Jupiter 12, Mars 15, Sun 19, Venus 8, Mercury 20, Moon 25, and you get 129. A twelfth of 129 years is 10 years 9 months. So every major period runs the same length, and the number that sets that length is the same number that distributes the sub-periods inside it.

Vettius Valens laid it out in the Anthology, Book IV in Mark Riley's translation (older editions number it Book V), with worked example charts. Hephaistio of Thebes carried it forward in his Apotelesmatika. Both treated it as a standard timing method alongside annual profections and zodiacal releasing.

The seven major periods are equal. Every planet rules for 129 months, full stop. The Sun does not get a longer turn than Venus at this level. What changes from chart to chart is the order, and the order is the part that takes real chart data to get right.

You start with the sect light. Day chart, the Sun goes first. Night chart, the Moon. From there you walk forward through the zodiac and hand the rulership to the next planet you meet by longitude, then the next, wrapping around the full circle until all seven have had a turn. The sequence is just your seven planets sorted by where they actually sit, rotated to begin at the sect light. Two people born the same week can run their decennials in completely different planetary orders. Augurine builds the order from the true longitudes in your chart, so the hand-off follows your planets rather than a generic list.

Inside each major period, the 129 months divide among the seven planets again, this time by their lesser years counted as months: Saturn 30, Moon 25, Mercury 20, Sun 19, Mars 15, Jupiter 12, Venus 8. Those add back to 129. The sub-period order starts with the major lord, then continues through the same chart-specific sequence. The major lord sets the terrain for the decade; the sub-lord tells you which stretch of road you are on inside it.

Valens went one level deeper. Each sub-period subdivides again into days, the partial times, using the same lesser-year proportions. Take Saturn's 30-month sub-period, which is 900 days: Saturn keeps about 209 of them, the Moon 174, Mercury 139, the Sun 132, Mars 104, Jupiter 83, Venus 55. Those are the whole-day counts; keep the hour-level fractions and the shares add back to exactly 900. This is where Valens and Hephaistio part ways. Valens keeps the exact fractions down to the hour. Hephaistio rounds each share up to a whole day, so his totals run a little over the frame. The calculator defaults to Valens and lets you flip to Hephaistio with a toggle.

Two planets speak at once, and the reading lives in how they get along. The calculator marks the major lord ruling your current decade and the sub-lord ruling the months inside it. Then go back to your birth chart and look at both as natal placements: the sign each is in, the house it occupies, whether it is in its own sect, and the relationship between the two.

When the major lord and sub-lord sit well together in the birth chart, a trine or a sextile between them, mutual reception, a shared sign, the sub-period tends to run with less friction. When they are at odds, the stretch usually asks for more deliberate effort to work both planets at once. None of this is a verdict on what will happen. It is a pattern, a quality of time you can plan around.

Run it backward before you trust it forward. Pull up the periods you have already lived and see whether the major-lord chapters line up with the actual chapters of your life. That retrospective check is how Valens himself argued the technique, and it is the fastest way to calibrate what a given planet's decade tends to feel like for you.

Decennials answer the decade. They are one layer in a stack, and they read best next to the others, which is how the Hellenistic astrologers used them.

The closest neighbor is firdaria. Both hand the seven planets a turn across roughly 75 years, and both key off sect. The difference is that firdaria periods are unequal and run in a set order, while decennial majors are equal and run in your chart's order. The Time Lord Calculator stacks your active rulers from several systems side by side, and zodiacal releasing starts from the Lot of Spirit for the longer narrative layer.

Yes, more than people expect for a technique that moves in decades. Sect is the hinge. A day chart starts the whole sequence on the Sun, a night chart starts it on the Moon, and that one switch can rewrite your entire period order and every hand-off date. Sect depends on whether the Sun was above or below the horizon at birth, which you can only know from the time. Near dawn and dusk the call gets genuinely close.

There is a second-order effect too. In a night chart the Moon leads, and the Moon moves about 13 degrees a day, so an uncertain time can nudge its longitude and shuffle where it lands in the order relative to the faster inner planets. If you do not have a verified time, a birth time rectification pass, or simply checking the past-period dates against your own history, will tell you fast whether the sect and order are landing right.