The nine-lord sequence
Vimshottari is a nakshatra-based period system described in chapter 46 of the Bṛhat Parāśara Horā Śāstra. That text lists the dasha lords beginning with Sun from Krittika; starting at Ashwini gives the equivalent cyclic order below. The nine durations total 120 nominal years. This is the length of the model’s complete cycle, not a statement about how long any person lives.
| Order | Lord | Nominal years |
|---|---|---|
| 1 | Ketu | 7 |
| 2 | Venus | 20 |
| 3 | Sun | 6 |
| 4 | Moon | 10 |
| 5 | Mars | 7 |
| 6 | Rahu | 18 |
| 7 | Jupiter | 16 |
| 8 | Saturn | 19 |
| 9 | Mercury | 17 |
Across the 27 equal nakshatras, the same nine lords repeat three times. Ashwini, Magha, and Mula begin Ketu periods; Bharani, Purva Phalguni, and Purva Ashadha begin Venus periods, and so on. The nakshatra overview explains the 13°20′ sectors.
How the birth balance is calculated
First calculate the Moon’s sidereal longitude at the recorded birth instant. Subtract the start longitude of its nakshatra, then divide by 13°20′. This gives the fraction of the nakshatra already traversed. Multiply that fraction by the starting lord’s full period to get the elapsed part. Subtract elapsed years from the full period to get the balance at birth.
For a simple arithmetic example, a Moon exactly halfway through Ashwini begins with Ketu. Ketu’s full seven-year period is half spent, so 3.5 nominal years remain. This example isolates the proportion; actual birth dates use an astronomical Moon position, not a manually rounded degree.
How antardashas are divided
Inside each major period, the subperiod sequence starts with that major lord and follows the same nine-lord cycle. A subperiod’s full nominal length is the parent period’s years multiplied by the sub-lord’s years, divided by 120. For example, Ketu/Ketu occupies 7 × 7 ÷ 120 = 0.408333 nominal years of a complete Ketu period. In the first major period, some subperiods may have ended before birth; the calculator displays only the portions remaining from birth onward.
Turning nominal years into dates
This site uses 365.2425 days per nominal year, the mean length of the Gregorian calendar year, and adds those durations to UTC timestamps. It does not count 360-day traditional years or advance by calendar anniversaries. All rows are half-open intervals: the start instant is included and the end instant belongs to the next period. The interface rounds displayed boundaries to the nearest second, but the arithmetic keeps fractional milliseconds. Local labels use the single fixed UTC offset supplied in the form, even decades later; historical or future civil time-zone changes are not modeled.
Another published calculator can use a different year length, rounding rule, ayanamsha, or ephemeris and show different dates while using the same ruler order. Drik Panchang’s Kundali has a Vimshottari Dasha view, but its date outputs should not be assumed identical to this stated convention.
Moon and birth-time uncertainty
Near a nakshatra boundary, even a small longitude or birth-time change can switch the opening lord and therefore all later rows. Away from a boundary, differences in Moon position still change the first balance and shift subsequent dates. The approximate Lahiri conversion used here is visibly named on the tool and in the ayanamsa guide. A missing birth time cannot give an exact birth balance under this method; find a reliable birth record before relying on the displayed sequence.
Text and computational sources
Chapter 46, verses 12–16 in the linked English Bṛhat Parāśara Horā Śāstra translation supplies the order, durations, and rule to subtract the elapsed portion from the first dasha. This link is to a modern translation of a traditional text; we do not reproduce its interpretive claims as astronomical facts. Moon positions come from the bundled Astronomy Engine 2.1.19 and this site’s approximate Lahiri conversion. The year-to-date choice and interval handling are implementation decisions declared above.