Methods and limitations
How Astrologram handles birth times, chart conventions, symbolic scores, and tarot reflections.
Astrologram · Reviewed ·
Birth charts
Astrologram separates astronomical positions, traditional chart conventions, and symbolic interpretation. Different choices of time zone, houses, or date boundary can produce different results from the same birth details.
Your local birth date and time are converted using the selected location’s time zone. Planet positions use Astronomy Engine’s Earth-centered vectors, transformed to the true ecliptic of date and divided into twelve tropical signs.
The chart uses equal houses: twelve 30-degree houses starting at the calculated Ascendant. The north node uses a mean-node formula. Major aspects are conjunction, sextile, square, trine, and opposition; the sextile orb is 6 degrees and the others use 8 degrees.
Other house systems, sidereal zodiacs, and true-node settings can give different results. Historical daylight-saving and time-zone behavior depends on the runtime time-zone database; historical civil-time ambiguities are not guaranteed to be resolved.
When the time is unknown
An unknown birth time uses 12:00 as a calculation assumption. If only the minute is unknown, the selected hour uses minute 00. Neither assumption recovers the actual birth time.
The app still generates the Ascendant and houses from that assumed time. Treat them as uncertain; the Moon and other positions can also differ across the day. A noon chart is not a confirmed-time chart.
Current calculation limits
The current midheaven output uses the start of the tenth equal house, rather than an independently calculated meridian Midheaven. Planet speeds and retrograde states are not fully calculated; those fields cannot establish whether a planet is retrograde.
These are implementation limits, alongside the chosen chart conventions. This page does not claim an independent accuracy benchmark or that symbolic interpretations are scientifically validated predictions.
Ziwei DouShu
Ziwei charts use iztro with a Gregorian date, birth time, and calculation sex. This flow uses the entered civil date and time without an additional birthplace time-zone conversion or true-solar-time correction.
The default year boundary is lunar New Year. With the default leap-month adjustment, days 1–15 keep the numbered lunar month; later days use the next month. You can instead keep the original lunar month.
Late Zi, 23:00–23:59, defaults to the next day. The app advances the whole Gregorian date before calculating with Zi hour, including month and year rollovers. You can instead assign late Zi to the same day. Different conventions can change a chart.
An unknown time also uses the noon assumption. It should not be treated as a chart with a confirmed birth-hour branch.
Scores and tarot
Fortune scores summarize app-specific symbolic rules involving stars, transformations, and palace relationships. They are not probabilities or empirically validated event forecasts. A higher score does not guarantee an outcome.
Tarot offers symbolic prompts for reflection. For an AI reading, the server sends your question, selected cards and orientations, and language to OpenRouter. Generated text can be wrong and should not replace professional judgment. Avoid including unnecessary personal details in your question.
How this page is reviewed
These descriptions were checked against the app implementation and its installed iztro 2.5.8 dependency. Upstream documentation may describe newer versions; that does not mean this app has their features. Method changes should be checked against both code and primary documentation before this page is updated.