Why two free birth charts can disagree
Compare the inputs before the interpretations. A practical guide to settings, missing data and what a paid file should add.
A chart screenshot can look authoritative while leaving its assumptions invisible. If two sites disagree, the useful first question is “what did each calculate?” A price tag alone cannot answer that. A free calculator can be perfectly adequate for a position lookup.
Make the comparison fair
- Copy the same input. Check the date format, local clock time, place and time-zone conversion. “Delhi, 8:30” is not a complete calculation record.
- Read the zodiac setting. Tropical and sidereal positions use different reference conventions. Within sidereal calculations, record the named ayanamsa.
- Check the house method. Comparing a whole-sign layout with a cusp-based display may compare different things even when the planetary degrees agree.
- Keep the source. Save settings alongside the result, rather than passing an unexplained screenshot to an AI.
The Swiss Ephemeris programming manual documents time conversion, sidereal modes and several house-calculation options. These are explicit calculation choices; a difference is not automatically a faulty website.
Separate three kinds of disagreement
Input: Were the birth details the same?
Computation: Were the settings and resulting degrees the same?
Interpretation: Did the readers draw different meanings from the same chart?
Only the last is a disagreement about the reading. Resolving the first two does not establish that an interpretation predicts real events. A precisely computed sky position and a reliable forecast are different claims.
What a paid file should add
Pay for inspectable work: organised calculations, a stated method, explanations of uncertainty and a document you can revisit. Ask to see an example before deciding. If all you need is a sign or degree, a free tool may already meet your need.
Astrodai’s files organise computed chart material into a reusable document. Compare the free sample with your own needs; do not buy because an unfamiliar term sounds impressive.