Planets via VSOP87
Planetary longitudes come from VSOP87 — the same high-precision planetary theory used by serious ephemerides — giving geocentric ecliptic positions, not rough averages. Pluto is computed from JPL Keplerian orbital elements.
Built on Real Astronomy
How Astro Precise Is Accurate
Most astrology apps stop at your Sun sign. Astro Precise computes the actual sky — the real positions of the Sun, Moon, and planets at your exact birth moment — using the same astronomical theory professional ephemerides rely on.
Every number is realThe Engine
Professional-Grade Astronomy
Under the hood, Astro Precise runs a genuine astronomical engine — not a lookup table of generic horoscopes. Here is exactly how each part of your chart is derived.
Moon via ELP2000
The Moon moves fast and irregularly, so it gets its own dedicated theory: ELP2000. That is why your Moon sign and degree are trustworthy even when you were born minutes from a sign boundary.
A True Ascendant & Midheaven
Your rising sign and Midheaven are derived from local sidereal time and the obliquity of the ecliptic — real spherical astronomy — not guessed from your Sun sign. This needs an accurate birth time and place.
Authentic House Systems
Choose how the sky is divided: Placidus (computed properly via right-ascension semi-arcs), plus Whole Sign, Equal, and Porphyry — each calculated the way classical and modern astrologers actually use them.
Real Retrograde Detection
Retrograde status is not looked up from a list — it is detected by sampling each planet's true motion across time, so retrogrades and the stations around them reflect the actual sky.
Historical Timezone Conversion
Your local birth time is converted to Universal Time using full historical timezone rules — including past daylight-saving shifts — so a chart cast for 1974 is as honest as one cast for today.
What "Accurate" Means Here
Arcminute Precision in the Computed Positions
The combination of VSOP87, ELP2000, and Meeus algorithms places the Sun through Pluto to roughly arcminute-to-degree precision, and Chiron — on a Kepler orbit from JPL elements — to the degree. Read that as an uncertainty band on the coordinates: typically within about an arcminute for the Sun and planets, widening toward a degree for the slowest and most distant bodies. It measures where each body sits, not how accurate any interpretation is — the difference between positions you can check against an ephemeris and a one-size-fits-all Sun-sign blurb.
Astrological meaning is tradition, offered for reflection and entertainment — not advice, prediction, or scientific fact. The astronomy underneath is computed and checkable.
Meeus algorithms throughout
Julian Day conversion, sidereal time, obliquity, and coordinate transforms follow the standard astronomical algorithms documented by Jean Meeus — the reference practitioners cite when they need it right.
Real aspects with real orbs
Aspects between planets are measured from the computed longitudes using standard orbs, and "applying versus separating" is determined from each body's actual daily motion — the same logic that powers your daily transits.
Deterministic, reproducible mapping
The same chart on the same day produces the same reading every time, everywhere. Nothing is randomised behind your back — each traditional interpretation is mapped to the computed positions by a fixed rule. The math fixes which passage of tradition you are shown; it does not make that meaning a measured or scientific fact.
Honest about its limits
When no exact transit touches your chart on a given day, Astro Precise says so. When a live feed is unavailable, it tells you instead of inventing a number. Accuracy includes admitting what isn't there.
The Ethos
“Every number on this site is real.”
That is the rule the whole project is built around. No fabricated data, no decorative figures, no fake precision. Where a value is computed, it is computed for real. Where a live feed (such as space-weather data) cannot be reached, the page says it plainly rather than filling the gap with a guess.
Privacy by Architecture
Your Birth Moment Never Leaves Your Browser
Accuracy and privacy are not a trade-off here. The entire engine runs on your device, so the most personal thing you enter — the exact moment and place you were born — stays with you.
No servers. No accounts. No tracking.
Every chart, transit, and reading is calculated in your browser. Astro Precise has no back-end of its own collecting your data, no analytics scripts, and no advertising trackers. Saved charts live in your own browser's local storage, on your device.
- Your birth date, time, and coordinates are processed locally and never transmitted to us.
- The only outbound requests are clearly-labelled public feeds (such as space-weather data) and a place-search lookup.
- Place search sends only the place name you type — for example "Lisbon" — never your birth moment.
- No login is required to cast a full, accurate chart.
Why It Matters
Sun-sign astrology asks one question — the month you were born — and gives everyone born in that month the same answer. A real chart asks for the full picture: the precise time, the place, and the whole sky overhead. The result is specific to you, grounded in astronomy you can verify, and presented with the care the subject deserves — factual, classy, and free of hype.
See It for Yourself
Cast a complete natal chart from real planetary positions — free, in your browser, with nothing to sign up for.
No account · No tracking · Computed on your device
Astrological meaning is tradition, offered for reflection and entertainment — not advice, prediction, or scientific fact. The astronomy underneath is computed and checkable.