How we calculate

Most astrology sites ask you to trust them. We'd rather show our work.

Real ephemeris, not a lookup table

Every chart here is computed from a professional-grade astronomical engine — the same class of planetary theory that powers observatory software, derived from NASA JPL solar-system data. Positions come out accurate to well under a tenth of a degree; in our test battery the worst case across a century of dates is under a hundredth of a degree.

Checked against independent software

Before anything shipped, the engine was verified against a fully independent professional astronomy library across twenty birth charts spanning 1923 to 2026 — northern and southern hemispheres, war-time clock rules, half-hour time zones, leap days. Signs, retrograde flags, rising signs, and midheavens all had to agree before the calculator went live.

The tropical zodiac, done properly

Sign positions use the tropical zodiac measured against the equinox of your birth date — the astrological standard. It's a subtle technical choice many tools silently get wrong by a fraction of a degree that grows every decade; ours is verified to agree with the reference computation to about a thousandth of a degree.

On your device, every time

The calculator runs entirely in your browser. The birth details you type are never transmitted, never stored, never logged — you can watch the network panel while it works and see nothing leave. The same inputs always draw the same chart, on any device, any day.

Honest edges

Where the truth is genuinely uncertain, the page says so: birthdays on sign boundaries are shown as the cusp dates they are (with the odds across a century of years), unknown birth times get an honest solar chart instead of a guessed rising sign, and daylight-saving anomalies are flagged rather than papered over.

Questions about the method are welcome — the whole point of computing in the open is that you don't have to take our word for any of it.