What the free jathagam shows
A jathagam (ஜாதகம்) is the Tamil word for a Vedic birth chart: the sky at the minute you were born, drawn as twelve houses. Zodian casts it from your date, time and place and shows the rasi chart (D1) with all nine grahas, the navamsa (D9) beside it, and a card of the facts every astrologer asks for first — your lagna, moon rasi, janma nakshatra with its pada, and the mahadasa and bhukti running today.
Positions are computed to the arcminute for the exact birth instant, with sidereal longitudes under the Lahiri (Thirukanitham) ayanamsa — the same defaults the Zodian app uses, so the free chart and a saved one always agree.
Lagna vs rasi: how to read the two
Your rasi is the sign the Moon occupied at birth. It names your janma nakshatra, sets the starting mahadasa, and is what Tamil daily rasi palan is written for. Your lagna (ascendant) is the sign rising on the eastern horizon at that moment — it fixes house one, and every other house is counted from it.
Read the lagna for the shape of a life (body, temperament, direction) and the rasi for the mind and its rhythms. When the two sit in different signs, an astrologer reads the chart from both and looks for what they agree on.
Why the birth time matters
The lagna changes sign roughly every two hours and the Moon moves about a degree every two hours, so an error of an hour can move the lagna into the next sign and shift the dasa dates by months. The date and place alone still give a reliable rasi and nakshatra most of the time — which is why the form lets you cast without a time and flags what may shift.
If you only have an approximate time, cast with your best guess, save the chart, and correct it later: every reading updates instantly.
South Indian or North Indian style?
Both draw the same chart. The South Indian square keeps each rasi in a fixed cell (Mesham always top row, second from left) and marks the lagna with a diagonal; the North Indian diamond keeps the lagna in the top-centre house and lets the rasi numbers rotate. Tamil, Telugu, Kannada and Malayalam readers usually prefer South; Hindi readers North. Switch anytime in the app.
Frequently asked questions
What does a jathagam show?
A jathagam is a Vedic birth chart: the positions of the Sun, Moon, Mars, Mercury, Jupiter, Venus, Saturn, Rahu and Ketu in the twelve rasis at your birth, plus the lagna (ascendant). From it come your moon rasi, janma nakshatra and pada, the navamsa chart, and the 120-year Vimshottari dasa timeline.
Do I need my exact birth time?
For the lagna, houses and precise dasa dates — yes, ideally to the minute. If you do not know it, tick "I don't know my birth time" and the chart is cast at 6:00 AM; your rasi and nakshatra are usually still correct, and you can fix the time after saving.
Which ayanamsa is used?
Lahiri (also called Thirukanitham in Tamil practice) by default — the standard used across Tamil Nadu and by Indian government almanacs. The Zodian app also offers True Chitrapaksha, Raman and KP (Krishnamurti) ayanamsas.
Is the jathagam free?
Yes. Casting here needs no account and costs nothing. Signing in with Google saves the chart and opens the full workspace — dasa timeline, planet strengths, yogas and doshas, porutham matching and PDF export — which is also free during beta.
South Indian or North Indian chart — which should I use?
They show the same positions. Use the style your family astrologer reads: South Indian (fixed rasi squares) is standard in Tamil Nadu and the south; North Indian (diamond, fixed houses) is standard in the Hindi belt. Zodian renders both.