Precise astrology
calculators
Exact dates and instants from genuine astronomy math — not month-rounded guesses. Free, private, and computed right here in your browser.
- No sign-up
- Nothing stored
- MIT astronomy-engine
Six calculators, real math behind each
Pick a calculation. Each one runs a genuine ephemeris search and explains what the result means.
Saturn Return
Find the exact dates of your first, second and third Saturn returns — including every retrograde pass.
Solar Return
The precise moment the Sun returns to its natal degree each year, in your birth or current timezone.
Rising Sign
Your ascendant and big three from an exact birth time and place — no guesswork on the cusp.
Birth Moon Phase
The Moon's phase and sign at the moment you were born, with what that lunar signature tends to mean.
Moon Phase Compatibility
Compare two birth Moon phases for an honest read on how your emotional rhythms fit together.
Mercury Retrograde
Exact station dates for every Mercury retrograde and shadow period — computed, not copied.
Why trust these numbers
Astronomy first, astrology second
Most astrology sites quote dates from generic tables or hand-wavy math. AstroCalcs computes each moment from the actual positions of the Sun, Moon and planets — then finds the exact instant your event occurs.
Real ephemeris, not lookup tables
Positions come from astronomy-engine (MIT), a rigorously tested model — never scraped tables or generic date math.
Exact instants, not month-rounding
We numerically search for the moment a planet hits its target, so returns and stations resolve to a date and time.
Private by design
Everything runs in your browser. Your birth data is never uploaded, stored, or attached to an account.
Transparent method
Each tool shows its assumptions and where birth-time precision matters, with a full methodology page.
Common questions
The short version: real math, no stored data, always free.
How accurate are these calculators?
Every result comes from real ephemeris math using the MIT-licensed astronomy-engine, the same class of positional model professional software relies on. We search for the exact instant a planet reaches a target, so you get a precise date and time rather than a month-rounded estimate.
Do I need my exact birth time?
It depends on the tool. Rising sign needs an accurate birth time and place. Saturn return, solar return and moon-phase tools work from a birth date alone, and each result is honest about where the exact time would sharpen the answer.
Is any of my birth data stored or sent anywhere?
No. Calculations run entirely in your browser. Your birth details never leave your device and nothing is saved on a server — there is no account and no tracking of what you enter.
Is it really free?
Yes. Every calculator is free to use with no sign-up. The site is static and runs the astronomy math client-side, so there is nothing to pay for.