How we calculate your chart

The calculation engine

Planetary positions are computed with Swiss Ephemeris, the reference library used by most professional astrology software worldwide. It's the same astronomical data source, not a simplified approximation.

The calculation engine is written and maintained directly for this site, built on top of that library — your chart is computed on our servers, never sent to a third-party service to be calculated.

How we verify our calculations

Before every update to the site, an automated test compares the calculation engine's output against an independent reference tool, position by position, on a test chart. If any discrepancy appears, the update isn't published until it's explained and fixed.

This isn't a marketing promise: it's a check that actually runs on every code change, not a one-time verification that gets forgotten.

Our method choices, explained

When an astrological notion can legitimately be computed in more than one way, we pick the method that's easiest to verify yourself rather than the most impressive-looking one — and we explain it instead of presenting it as a black box.

For example, chart dominants (elements, modalities) are calculated with a simple, unweighted count of the classical planets — a method you could reproduce by hand — rather than a proprietary weighting whose formula would never be published.

What we don't calculate, and why

Some elements simply can't be calculated without precise information, and the site says so plainly rather than inventing an approximate value:

• Without an exact birth time, the Ascendant, Midheaven, and houses are not shown — guessing them would produce a wrong result, not just an imprecise one.
• Chiron is not calculated: the astronomical data file this point requires isn't available in our current Swiss Ephemeris setup.