How it works

A Vedic chart measures the zodiac from a point fixed against the stars, not from the March equinox. The difference between the two zero points on a given date is called the ayanamsa. This calculator uses the value this page calls Lahiri, as the Indian Astronomical Ephemeris computes it: a formula in time that gives 23 degrees 51 minutes 25.53 seconds at the start of the year 2000.

The ephemeris states its starting point as the equinox of AD 285, and fixes the difference at 23 degrees 15 minutes at the start of 21 March 1956. Its formula comes out about 16 seconds of arc below that figure on that date, and we use the formula, as a mean value, for every date. The Calendar Reform Committee's report of 1955 set this standard. We could not read the part of the report with the adopted wording, so we describe the ephemeris's numbers and leave the rest aside.

Lahiri is one of several zero points. Six different values were in print in Indian almanacs for a single date in 1883, and the old texts do not agree on one. Another calculator with a different zero point will show every position moved by the same small amount.

The scanned text of the ephemeris reads one small coefficient of the formula ten times too large. We use the corrected value, and for the dates this calculator covers the difference is under a thousandth of a second of arc.

The Sun, Moon and five planets start as the same apparent positions the birth chart section calculates, with the zero point subtracted. Those positions keep a small wobble of the Earth's axis, up to about 17 seconds of arc, and the ayanamsa here is a mean value that does not. A calculator that uses a true ayanamsa will differ by about that much.

The ascendant, here called the Lagna, comes from the same calculation with the zero point subtracted. The nakshatras are 27 equal arcs of 13 degrees 20 minutes starting at zero, each divided into four padas, and the navamsa follows the rule in the Brihat Jataka and the Brihat Parashara Hora Shastra.

Rahu and Ketu are the two points where the Moon's path crosses the ecliptic. The Surya-Siddhanta gives only the node's average motion, and the Indian ephemeris tabulates a mean Rahu, so this calculator uses the mean node, with Ketu at the point opposite it. None of the old texts we checked names a true node. Using the mean node is our choice, and a calculator using the true node can show a difference of more than a degree.

The bhavas, or houses, are whole signs counted from the rashi of the Lagna, as the Brihat Jataka counts them. Other ways of dividing the houses exist, and the Brihat Jataka's translator mentions a separate house chart, but no method for one is described in what we read.

Without a birth time there is no Lagna, so no bhavas are shown, and no birth time is assumed for them.

Exaltation, debilitation, own rashi and mulatrikona come from the Brihat Jataka, and this page records them by rashi alone. The degree limits for mulatrikona appear only in the Sanskrit of the Brihat Parashara Hora Shastra and are not used. Where a rashi carries more than one dignity, all are listed. The sources state no such rule for Rahu and Ketu.

The order and lengths of the periods, which total 120 years, come from chapter 46 of the Brihat Parashara Hora Shastra, in a typed Sanskrit text whose edition we could not identify, and from a note by N. Chidambaram Iyer in his translation of the Brihat Jataka, which also describes the starting balance. The typed Sanskrit gives Mercury 19 years where every other source gives 17, a total of 122, and we use 17. The Brihat Jataka's own dasha scheme is a different one, and Iyer says it was hardly studied by his time.

The first lord is the lord of the Moon's nakshatra at birth, and the balance is the unfinished part of that nakshatra. The texts we checked do not set the length of a dasha year, so counting a year as 365.25 days is this calculator's choice. A period marked as running is marked only by the date on your device when you press Calculate.

Charts are drawn in the South Indian layout, with the rashis in fixed squares and Meena at the top left. It is documented in 1885 and 1912 in the books we read. The North Indian diamond is not offered because we could not confirm it in anything we checked, and a line in the corner of a square here marks the Lagna.

This page shows no Mangal Dosha check, no Sade Sati, no Kala Sarpa and no gemstone advice, and it makes no predictions. The Brihat Parashara Hora Shastra does list the houses for Mars, as the Mangal Dosha page explains, but this calculator runs no test on them. We found no rule called Sade Sati in the books we read, though we did not read the chapters on transits, and we have not checked those books for Kala Sarpa. Your birth date, time and place stay in your browser.

Read what the texts say on Mangal Dosha