Sade Sati, Ashtama and Kantaka Shani: calculating exact dates

Published 9 Oct 2026

This article shows how to turn a natal Moon sign into a list of dated Saturn cycles: the three phases of Sade Sati, Ashtama Shani and Kantaka Shani. You will see how to get the ingress dates, how retrograde re-entries split a cycle into several intervals, and why two programs can disagree by a few days.

Definitions

Natal Moon sign (Janma rasi). The sidereal sign the Moon occupies at birth. All counting here starts from it, with the Moon sign as the 1st.

Gochara. Transit. The current positions of the planets, read against the natal chart.

Sade Sati. Literally "seven and a half". The period while Saturn transits the 12th, 1st and 2nd signs from the natal Moon. Saturn takes roughly two and a half years per sign, so the three signs together take about seven and a half years. Saturn's full round of the zodiac takes about 29.5 years, so Sade Sati returns at about that interval.

Phases of Sade Sati. Rising: Saturn in the 12th from the Moon. Peak: Saturn over the Moon sign itself (the 1st). Setting: Saturn in the 2nd from the Moon.

Ashtama Shani. Saturn transiting the 8th sign from the natal Moon.

Kantaka Shani. Saturn transiting a kendra (angle) from the natal Moon. Here that means the 4th, 7th and 10th.

Ingress. The moment a planet crosses from one sign into the next.

Retrograde re-entry. When Saturn crosses into a new sign, turns retrograde, moves back into the previous sign, and later crosses forward again. Each crossing starts a new interval.

Ayanamsa. The offset between the tropical and sidereal zodiacs. Lahiri (Chitrapaksha) is the most common choice in India; KP uses the Krishnamurti ayanamsa, which is very close to Lahiri.

The method, step by step

Step 1: Fix the natal Moon sign

Calculate the Moon's sidereal longitude at birth with your chosen ayanamsa and note its sign. The Moon's degree does not matter for the sign-based method, but check it if the Moon is very close to 0° or 30°: an error in birth time or ayanamsa near a boundary can change the sign, and with it every date that follows.

Step 2: Map Saturn's transit sign to a cycle

Count from the Moon sign (as 1) to Saturn's transit sign:

So in a full round of about 29.5 years, Saturn spends seven of its twelve signs in one of these cycles.

Step 3: List Saturn's sign intervals over the period you need

Work out every interval Saturn spends in one sign, from one crossing to the next, over your date range. Do not assume one interval per sign. Near a sign boundary Saturn often crosses forward, retrogrades back, and crosses forward again, which gives three intervals instead of two.

A reliable way to do this with an ephemeris:

1. Step through the range one day at a time and note Saturn's sidereal sign each day.
2. Wherever the sign differs from the previous day, a crossing happened in that 24-hour gap.
3. Narrow the gap by bisection (check the midpoint, keep the half where the change happens) until you are down to the minute.

A daily step is safe for Saturn: it moves only a few arc-minutes a day, and it never crosses a boundary and comes back within a single day.

Step 4: Label each interval and keep them separate

Apply the table from Step 2 to each interval. Keep retrograde re-entries as separate rows rather than merging them. An astrologer reading the list should be able to see that Saturn left the peak sign, came back for some months, and then left for good.

Step 5: Report dates in a stated time zone

An ingress found to the minute in UTC can fall on the next calendar day in IST (UTC+5:30) if it happens late in the UTC day. Say which time zone your dates use.

AstroReads follows this method. It lists Saturn's sidereal sign intervals with a daily scan, finds each crossing to the minute by bisection, keeps retrograde re-entries as separate intervals, and maps each interval to a cycle with the table above, using the Lahiri ayanamsa, which is fixed in the product for now. In a client brief, each cycle that overlaps the timeline is listed with its true start and end, even if it began years before the timeline. When the birth time is unknown, it checks the Moon's sign at the start and end of the birth date; if the sign is the same, the Saturn cycles are still given, because they depend only on the Moon sign. If the Moon changed sign that day, it gives no cycles and flags that the birth time is needed.

Worked example

Both charts are fictional births, used only to illustrate the method. Dates were computed with the Lahiri ayanamsa over a window from 1 January 2018 to 1 January 2036, and are UTC calendar dates. A date of 2018-01-01 or 2036-01-01 is the edge of that window, not a real ingress.

Example B: Sade Sati with a retrograde re-entry

Example B is born 02 Aug 1993, 21:45 IST, Lucknow. The natal Moon is at Capricorn 18°33′, so the Moon sign is Capricorn. Counting from Capricorn: Sagittarius is the 12th, Capricorn the 1st, Aquarius the 2nd, Aries the 4th, Cancer the 7th, Leo the 8th and Libra the 10th.

Look at the middle of the Sade Sati. Saturn entered Aquarius on 2022-04-29, which starts the setting phase. It then turned retrograde and moved back into Capricorn on 2022-07-12, so the peak phase resumed. It crossed into Aquarius again on 2023-01-17 and stayed there until 2025-03-29, when it entered Pisces (the 3rd from Capricorn, not a cycle sign) and Sade Sati ended.

The sequence setting → peak → setting is not an error. It is exactly what Saturn did in the sky. If you merge it into one "setting from 2022-04-29" row, you lose the fact that Saturn was back over the Moon sign for about six months. If you take only the final ingress, you report the setting phase as starting on 2023-01-17 and miss the first entry. Listing all three rows keeps both pieces of information.

The Aries Kantaka (4th from Capricorn) also shows re-entries. Saturn entered Aries on 2027-06-02, went back into Pisces from 2027-10-20 to 2028-02-23, re-entered Aries, briefly crossed into Taurus between 2029-08-08 and 2029-10-05, and returned to Aries until 2030-04-17. The gaps between the rows are the times Saturn was in Pisces or Taurus, neither of which is a cycle sign from Capricorn.

Example B's Ashtama (Saturn in Leo) falls after the end of this window.

Example A: the same transits, different labels

Example A is born 14 Mar 1990, 06:20 IST, Pune. The natal Moon is at Virgo 28°28′, so the Moon sign is Virgo. Counting from Virgo: Sagittarius is the 4th, Pisces the 7th, Aries the 8th and Gemini the 10th.

Compare the two examples. Saturn's dates are the same for everyone, because it is one planet in one sky: it is in Aries from 2027-06-02 to 2027-10-20 for both people. What changes is the label. For Example B (Moon in Capricorn), Aries is the 4th, so the interval is Kantaka. For Example A (Moon in Virgo), Aries is the 8th, so it is Ashtama.

Example A also shows a retrograde re-entry between two different cycles. Saturn moves from Pisces (Kantaka) into Aries (Ashtama) on 2027-06-02, back into Pisces (Kantaka) on 2027-10-20, and into Aries (Ashtama) again on 2028-02-23. Between 2029-08-08 and 2029-10-05 Saturn was in Taurus, the 9th from Virgo, so no cycle is listed for those weeks.

Example A's Moon is at 28°28′ Virgo, close to the end of the sign. The Moon sign is still Virgo, and that is all the sign-based method uses. Under a degree-based definition (see below) the placement within the sign would shift the dates. Example A's Sade Sati (Saturn in Leo, Virgo and Libra) falls after the end of this window.

Where traditions differ

Moon sign or lagna? Sade Sati, Ashtama and Kantaka Shani are defined from the natal Moon sign in the usual practice, because gochara results are classically read from the Janma rasi. Some astrologers also track Saturn's transit from the lagna and read it alongside. That is a valid second view, but it is a different calculation, and its dates will not match those counted from the Moon. AstroReads counts these cycles from the Moon sign only.

Which ayanamsa? The sign Saturn occupies depends on the ayanamsa, so every ingress date does too. Lahiri and Krishnamurti differ by only a few arc-minutes, and in practice their Saturn ingress dates usually differ by a day or two. Ayanamsas that differ by a degree or more, such as Raman, can move ingress dates by weeks. Near a station, a small shift in the ayanamsa can even decide whether a short retrograde re-entry happens at all. Lahiri is fixed in the product for now; the other choices are legitimate.

Does Kantaka include the 4th? Kantaka Shani is usually described as Saturn in a kendra from the Moon. Since the 1st is already the peak of Sade Sati, the remaining kendras are the 4th, 7th and 10th, which is what this method uses. Many astrologers give the 4th its own name, Ardhashtama Shani ("half of the 8th"), and treat it separately. Others apply the Kantaka label only to some of the kendras. The dates do not change, only the label.

Sign-based or degree-based Sade Sati? The method above uses whole signs: Sade Sati begins when Saturn enters the 12th sign from the Moon and ends when it leaves the 2nd. A degree-based definition instead counts Sade Sati while Saturn is within 45° of the natal Moon's exact longitude on either side. That span is also 90°, so the total length is similar, but the dates shift with the Moon's degree. For Example B, with the Moon at 18°33′ Capricorn, the degree-based window would run from Saturn at 3°33′ Sagittarius to Saturn at 3°33′ Pisces, so it starts and ends later than the sign-based dates. Both definitions are in use.

How much weight to give a cycle? Practice differs on how strongly these transits count on their own. Many astrologers read them only together with the running dasha, Saturn's natal strength and its Ashtakavarga bindus in the transit sign. The engine lists the cycles as dated facts; their weight in a reading is the astrologer's call.

Common mistakes

• Using the tropical zodiac. Western ephemerides give tropical positions. Sade Sati dates must come from sidereal positions, or every date will be off by roughly two years.
• Reporting one interval per sign. Retrograde re-entries are common at Saturn's sign boundaries. Example B's 2022–2023 setting → peak → setting sequence is a typical case.
• Counting from the Sun sign or the lagna and calling it Sade Sati. The standard definition uses the Moon sign.
• Ignoring time zones. A UTC date and an IST date can differ by one day for the same ingress.
• Using a fixed "7.5 years from the first ingress". Saturn's speed varies, and retrogrades stretch or shorten each phase. Calculate every boundary from the ephemeris.
• Describing the cycle in alarming terms. Present the cycles plainly, with dates, as one input among several, and read them with the dasha rather than on their own.

Sources

• Brihat Parashara Hora Shastra: the nature of Saturn and the framework of the natal chart used for transit reading.
• Phaladeepika: its treatment of gochara, the results of planets transiting each house from the natal Moon.
• Saravali and Jataka Parijata: the significations of Saturn.
• K.S. Krishnamurti, KP Readers I–VI: the Krishnamurti ayanamsa, and the KP practice of reading transits together with the running dasha periods.