Astrology cycle calculators
Exact cycle dates computed from your birth date. No account, and no birth time needed for the slow-planet cycles.
Each calculator here takes a birth date and returns dates: the instants a slow-moving planet reaches a named angle to the degree it held when you were born, and the span either side in which it is within orb. The positions are Skyfield/JPL DE440 positions — the same ones every other page on this site computes from — and the ages are measured across a range of birth years rather than rounded to a familiar number.
See every one of these cycles dated in your own chart
The calculators
| Calculator | What it dates | You enter | Measured shape |
|---|---|---|---|
| Saturn return | Transiting Saturn back on your natal Saturn | Your birth date | first at 28.4–29.9, median 29.5 · 33% triple |
| Jupiter return | Transiting Jupiter back on your natal Jupiter | Your birth date | next at 23.2–71.7, median 47.7 · 17% triple |
| Mercury retrograde | Every Mercury station and the arc it retraces | Nothing (a date for the personal half) | 3/yr · 20–24 d, median 23 |
| Uranus opposition | Transiting Uranus opposite your natal Uranus | Your birth date | first at 39.7–44.1, median 43.1 · 91% triple |
Computed 2026-09-14 · Skyfield 1.55 + JPL DE440 via POST /api/scan · 3° canonical envelope (CANONICAL_PRESSURE_ORB). Each page recomputes its own tables from the same snapshot; the calculator on it runs live. Recomputed on every deploy.
How these work
Two shapes, and the question decides which one you need
A cycle calculator answers a question about your own chart: transiting Saturn crossing your natal Saturn, transiting Uranus reaching the point opposite its birth position. The geometry is the same in both cases and only the angle differs, but the answer is personal, because it depends on the degree the planet occupied on your birth date. Those ask for a birth date, and they answer before they ask for anything else.
A retrograde calculator answers a question about the sky, and the sky is the same for everybody. Mercury stations retrograde when it stations retrograde; the dates and the arc it retraces are public, and the table on that page is dated without any input at all. What is personal there is narrower and more interesting — which of your own degrees sit inside the arc the planet is about to re-cross — and that is what the calculator on the page computes.
Why none of these asks for a birth time
A birth time places the Ascendant, the Midheaven and the Moon, and it places them sharply: the Ascendant moves roughly a degree every four minutes. None of those is what these calculators date. The bodies here are slow — measured on the daily baseline, the fastest of them covers at most 14.5 arcminutes in a day and the slowest 3.8 — so a birth hour nobody recorded moves the crossing date by well under a day, which is smaller than the difference between two published tables. Positions are computed for noon UTC and every page says so.
That is a limit, not a licence. There is no rising-sign calculator here, and there will not be one that takes a date alone: the honest answer to "what is my rising sign" needs the time and the place, and a page that guessed would be confidently wrong for most of the people who asked.
Why one contact can carry three dates
A planet does not cross a degree once and move on. It crosses, stations retrograde some weeks later, backs over the same degree, stations direct and crosses a third time — so one Saturn return can be three exact dates spread across ten months, and the middle one is the retrograde crossing. The count is always odd. Two is geometrically impossible, because a planet that comes back has to leave again.
The tables here say which count each row has, and where the engine could not prove it they say that instead of printing a number. That refusal is deliberate: a crossing count is derived from watching the planet depart the contact point on both sides, and when the searched range does not reach far enough to see it depart, the honest output is the crossings found plus the fact that the total is unproven.
One engine, two ways of reaching it
The dated tables on each page come from a snapshot committed to the repository and regenerated deliberately, so the build never depends on a server being awake and the numbers are reviewed in a diff like any other content. The calculator on each page runs live against the same Skyfield/JPL DE440 endpoints the app itself uses. They are not two sources that might disagree — the arithmetic between them is one module, so the table is the answer at birth-year resolution and the calculator is the same answer at yours.
See every one of these cycles dated in your own chart
Common questions
- Which astrology calculator do I need?
- If the question is about a date in your own life — when your Saturn return lands, when your Uranus opposition falls — use one of the cycle calculators and enter a birth date. If the question is about the sky itself, such as when Mercury stations retrograde, the retrograde page is dated without any input, and its calculator answers the personal half: which of your degrees the retrograde arc re-crosses.
- Do these calculators need my birth time?
- No. The bodies here move slowly enough that an unrecorded birth hour shifts a crossing date by well under a day — at most 14.5 arcminutes daily for the fastest of them, 3.8 for the slowest. Birth time matters for the Ascendant, the Midheaven and the Moon, and no calculator here offers those from a date alone.
- Do I need an account to use them?
- No. Every calculator on this site computes and shows the full result with no account and no email. Your birth date is sent to the ephemeris endpoint to compute a position and is not stored, not put in the URL, and not attached to any event.
- Why does my return have three dates instead of one?
- Because the planet crossed your degree, stationed retrograde and backed over it, then turned direct and crossed a third time. One contact, three exact instants, often spread across ten months. The count is always odd — never two — and each calculator labels which pass is which.
- Are these the same dates the app shows?
- Yes. The tables are computed from a committed Skyfield/JPL DE440 snapshot and the calculators run live against the endpoints the app uses, through the same arithmetic module. The app adds what a single page cannot: every cycle at once, on one timeline, with the surrounding pressure measured rather than described.
This is one cycle. See all of yours.
Cosmic KPI computes every cycle in your chart from your birth details — exact dates, visible math, your own chart. No account needed to start.
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