What is the lagna?
As the Earth turns, each of the twelve signs rises in turn over the eastern horizon, one after another through the day. The sign rising at the moment of your birth, seen from your birthplace, is your lagna or ascendant. It becomes the first house of your chart; the next sign is the second house, and so on round the circle.
Because the houses are counted from it, the lagna decides which part of life each planet speaks to — work, home, partnership, wealth. That is why astrologers treat the lagna, not the Sun sign, as the backbone of a Vedic chart.
Why the birth time must be accurate
All twelve signs rise in about 24 hours, so on average a sign stays on the horizon for about two hours and the lagna moves one degree every four minutes. Some signs rise faster than others, and the speed changes with latitude. If you were born near the change from one sign to the next, a few minutes of error can change the lagna — and with it every house in the chart.
Hospital records and birth certificates are the best source. Family memory ("around sunrise") is useful but approximate. When the lagna is within two degrees of a sign boundary we say so, so you know how much to trust it.
Lagna, rashi and Sun sign — three different things
These three are often confused. Each is a different point in the same chart:
- Lagna (ascendant): the sign rising at birth — the self, the body, the frame of the whole chart. Changes every ~2 hours.
- Rashi (Moon sign): the sign the Moon was in — the mind and daily experience. Changes every ~2¼ days.
- Sun sign: the sign the Sun was in — the soul and vitality in Vedic reading. Changes about once a month.
The lagna lord
The planet that rules your lagna sign is the lagna lord (lagnesh). The house it occupies shows where your energy naturally goes: in the tenth it leans towards work and public life, in the fourth towards home, in the seventh towards partnership. It is a classical first thing to look at, and the calculator shows it for you.
How we calculate it
We compute local sidereal time for your birthplace's longitude, find the ecliptic degree rising on the eastern horizon at its latitude, and subtract the Lahiri ayanamsa. The birth time is read in your birthplace's time zone with its historical offsets. Our lagna agrees with the Swiss Ephemeris to within a few arcseconds. No AI is involved in the calculation.