Navamsha (D9) — the chart read for marriage

What this computes

Each of the twelve signs spans thirty degrees. Divide that span into nine equal parts of three degrees and twenty minutes each, and every planet sits in one of them. Each part is then mapped onto a whole sign of its own. Do this for all nine grahas and the ascendant and you have the navamsha, or D9 — the ninth divisional chart. This page computes it from the same sidereal longitudes that produce your birth chart, and draws the two side by side so the difference is visible rather than described.

The mapping is not arbitrary. Counting runs continuously through the zodiac, which is why the nine parts of a movable sign begin at that sign itself, the nine parts of a fixed sign begin at the ninth from it, and the nine parts of a dual sign begin at the fifth. Those three rules are one rule stated three ways.

The part that usually goes unsaid

The D9 adds no new measurement. Every navamsha position is a fixed arithmetic function of a longitude already in the birth chart, so nothing enters the D9 that was not already there. What the division does add is magnification — and it magnifies the uncertainty along with everything else.

A navamsha boundary is crossed nine times as often as a sign boundary, so a birth time precise enough to fix your lagna may not be precise enough to fix your navamsha lagna.

If the recorded time is rounded to the nearest quarter hour, the birth chart may be untouched while the D9 ascendant moves. In our sampled JPL comparison, the largest Sun-through-Saturn position difference was 0.44 arc-seconds. This does not validate every D9 or ascendant calculation; compare birth inputs, ayanamsa and the divisional-chart convention when reports disagree.

What the result does and does not mean

Several traditions weigh the D9 heavily in marriage questions, and some read a planet that occupies the same sign in both charts — vargottama — as a strengthened one. Those are conclusions those traditions draw. This page draws the chart; it does not tell you what your marriage will be like, and no divisional chart on its own constitutes a verdict.

A refusal built partly on the D9 rests on three things: the birth time, the ayanamsa, and the interpretive rule applied afterwards. The first two are checkable here. The third is a matter of stated tradition, and asking which one was used is a reasonable question.

Why does my D9 differ from the one I was shown?

Usually one of three reasons. A different ayanamsa shifts every longitude by a similar amount, which is enough to move a planet sitting near a three-degree-twenty boundary. A different birth time moves the ascendant fastest. And some charts are drawn in the North Indian diamond and some in the South Indian square, which can make identical charts look unrelated at a glance.

Do I need an exact birth time?

For the planets, no — the Moon is the fastest of them and still takes hours to cross a navamsha. For the navamsha ascendant, yes, more than the birth chart requires. If your time is approximate, treat the D9 ascendant as the least settled thing on the page.

Is the D9 stronger than the birth chart?

Traditions differ, and the disagreement is old. Some hold that a promise in the birth chart is only realised if the D9 supports it; others treat the D9 as one input among several. Both positions are documented, and neither can be settled by computation.