Narayana Dasha is also sign-based, but it appears in Parashara's classical text (Chapter 46) and uses different seed and duration rules than K.N. Rao's Chara Dasha. Both are "Jaimini Sutras" in spirit, but they are NOT the same.
Narayana Dasha may start from Lagna, or from the 7th, or whichever is stronger—creating different timelines even for the same birth chart. Duration is calculated similarly to Chara (sign → lord), but Parashara adds special rules:
• Lord in own sign = 12 years (same as Chara).
• Lord exalted = add 1 year to the duration.
• Lord debilitated = subtract 1 year.
• Lord retrograde = special adjustments (varies by commentary).
Antardasha in Narayana uses fixed 12-part divisions (not proportional like Vimshottari), so each antardasha is 1/12 of the mahadasha period.
Key difference from Chara: Narayana is more conservative; it respects classical Parashara strength (exaltation, debilitation) and adds/subtracts years accordingly. Chara is more purely positional (count from sign to lord).
When should you use Narayana vs Chara? Both. Jaimini scholars debate which is "correct." The pragmatic approach: compute both and see which one aligns with your client's life events. Some charts respond to Chara; others to Narayana.
The calculator computes Narayana periods. You will compare Narayana and Chara timelines for the same chart to see which correlates better with known events.