The birth chart

Three coordinates, and why each matters

Date

Fixes where the slow planets are. Saturn moves through one sign in about two and a half years, so the date alone settles a great deal of the chart.

Time

Fixes the ascendant, and therefore every house. The ascendant advances a full degree every four minutes and a whole sign roughly every two hours. This is the input people are least sure about and the one that changes the most.

Place

Fixes the horizon the ascendant is measured against, and supplies the time zone — including historical rules, which matter more than people expect. India ran at UTC+06:30 from 1942 to 1945, and a wartime birth computed with today's +05:30 is a full hour wrong.

Vedic charts are sidereal

Western astrology measures from the spring equinox. Vedic astrology measures from the fixed stars. The two coincided around the fifth century and have drifted apart since, at about fifty arcseconds a year — roughly 24° by now. That gap is the ayanamsha, and it is why your Vedic sign is usually the one before your Western one, and why the Sun enters sidereal Aries in mid-April rather than on 21 March.

What you get here

• Planetary positions. Sidereal longitude, nakshatra, pada, retrogression, combustion and classical dignity for all nine grahas.
• Houses. Under whole-sign by default — what classical Vedic prediction assumes — with equal, Sripati and Placidus also available.
• Divisional charts. All sixteen, D1 through D60, each by the rule its own tradition specifies.
• Vimshottari dasha. Mahadasha, antardasha and pratyantardasha with exact dates.
• Yogas and doshas. Every rule showing the conditions it checked and the classical cancellations that apply.

For how the calculations are done and how they are checked, see how it works.