The calculator starts with your birth date, birth time, birth location, and timezone. After the astrocartography map is generated, the city check compares a selected city with visible planetary line paths on that map.
A city result or comparison can include the nearest planetary line, angle, approximate distance, strength band, support signal, caution signal, and interpretation theme. AI reading can use those calculated signals as context, but it does not calculate new line distances, invent map signals, or rerank cities inside the report.
For a full walkthrough, see the chart example. For calculation details, read the methodology page.