Question 1

What does the Vedic Sun sign calculator tell you?

Accepted Answer

Your sidereal Sun sign using Lahiri ayanamsa.

Question 2

How does Ganak calculate this?

Accepted Answer

Ganak computes every figure from an ephemeris for the place and moment you give it, rather than reproducing a published almanac. The sidereal frame is the Lahiri ayanamsa and the lunar nodes are mean Rahu and Ketu — the defaults Drik Panchang uses — and they are never switched silently, because doing so would change every chart in the app. Calendar conventions stay separated rather than blended: Amanta and Purnimanta month reckoning, Tamil solar (Lahiri sidereal ingress with the Tamil sunset rule) and Bengali solar (Vishuddha Siddhanta with the Bengal next-sunrise rule) are each selected explicitly and named on the page that uses them.