Chara Dasha is entirely sign-based, not star-based like Vimshottari. "Chara" means "moving"; the sequence of dasha signs and their durations move and change based on two variables: the native's Lagna modality and where each sign's lord is placed.
K.N. Rao's method (most widely used):
If Lagna is Savya (odd-numbered, moveable: Aries 1, Gemini 3, Leo 5, Libra 7, Sagittarius 9, Aquarius 11), dashas proceed forward through the zodiac: Aries → Taurus → Gemini → ... If Lagna is Apasavya (even, fixed: Taurus 2, Cancer 4, Virgo 6, Scorpio 8, Capricorn 10, Pisces 12), dashas proceed backward: Taurus → Aries → Pisces → ...
Duration = count from dasha sign → dasha sign's lord (in the appropriate direction) minus 1 year. Example: Aries lord is Mars. If Mars is in Gemini, count Aries (1) → Taurus (2) → Gemini (3); duration = 3 - 1 = 2 years. If Mars is in Aries (own sign), duration = 12 years (standard rule).
This produces dasha periods that range from 1 to 12+ years, far more variable than Vimshottari's fixed cycles. Some years are short, others long, reflecting karmic intensity in that sign's domains.
Scorpio and Aquarius have dual lords (Mars+Ketu for Scorpio, Saturn+Rahu for Aquarius). The calculator uses the stronger of the two for duration calculation.
The engine computes Chara Dasha periods for the entire life. You will track dasha transitions and correlate them with major life events to test the system's accuracy on your own charts.
A dasha of signs. Vimshottari runs planetary periods from the Moon's nakshatra. Chara Dasha runs sign periods, and the length of each is derived from the chart rather than from a fixed table. This makes Chara Dasha specific to the individual in a way Vimshottari is not.
Direction first. The lagna's modality determines whether the sequence runs forward (Savya) or backward (Apasavya). Getting the direction wrong inverts the whole timeline, so this is the first thing to establish and the first thing to check when a Chara reading fails to match a known life.
Computing the length. Count from the sign to its lord; the number of signs gives the period in years, with defined adjustments. A sign whose lord sits close by therefore gets a short period, and one whose lord is distant gets a long one. Periods range from one to twelve years.
Why practitioners use it. Because the durations vary by chart, Chara Dasha often marks life chapters that Vimshottari smooths over. Many practitioners run both and treat agreement between them as a strong timing signal.