How a chart is cast and drawn

What happens between "born 7:45 in Jaipur" and a kundali?

The steps of the calculation

1Birth detailsdate, time, place

2To UTCtime zone and any DST or war time removed

3Julian Dayone running day count

4Ephemeriseach planet's longitude

5Ascendantfrom star time and latitude

6Ayanamshatropical → sidereal

7Houses, nakshatras, vargasall worked out from the longitudes

Julian Day is a single count of days since noon on 1 January 4713 BC. Astronomers use it because it has no months, leap years or calendar changes to trip over. 1 January 2000 at noon is day 2,451,545.
The ascendant comes from local sidereal time (star time at your longitude) and your latitude, using spherical trigonometry: which degree of the ecliptic is crossing the eastern horizon right then.
Houses: most Vedic astrologers use whole-sign houses: the rising sign is the whole 1st house, the next sign the whole 2nd, and so on. Other systems cut the houses at exact degrees (see Bhava Chalit below, and Placidus in the KP chapter).
Planetary degrees: each planet's longitude gives its sign (every 30°), its degree in the sign, its nakshatra (every 13°20′) and pada (every 3°20′).

Four ways to draw the same chart

North IndianA square cut into diamonds and triangles. The houses stay put (house 1 is the top diamond) and the numbers written in them show which sign sits there. Read anticlockwise.

South IndianA 4 × 4 grid with the middle empty. The signs stay put (Pisces top-left, Aries next to it, then clockwise) and the ascendant is marked with a line or "Asc".

East IndianUsed in Bengal and Odisha. Signs are fixed too, with Aries in the top-middle box, counting anticlockwise.

Western wheelA circle. The ascendant is on the left (9 o'clock), houses run anticlockwise, and aspect lines are drawn across the middle.

All four show exactly the same information. Pick the one you were brought up with.

Rashi, Bhava and Chalit charts

Rashi chart: the ordinary birth chart (D1), showing which sign each planet is in.
Bhava chart: a chart of the houses measured from the exact ascendant degree. The middle of each house (bhava madhya) is 30° apart, starting at the ascendant degree.
Chalit chart (Bhava Chalit): the rashi chart redrawn so that a planet near a sign edge can move into the next or previous house, while keeping its sign. Astrologers check it when a planet sits at the very beginning or end of a sign.

charts are drawn North-Indian style with whole-sign houses, from the Swiss Ephemeris and the Lahiri ayanamsha.

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