Mahadasha vs Antardasha: Main Period and Subperiod
Understand the difference between mahadasha and antardasha, calculate a subperiod’s share, and avoid restarting subperiods at birth.
Overview
A mahadasha is a main period; an antardasha is one of its nine subdivisions in Vimshottari. A two-ruler label places the main ruler first and the subperiod ruler second. Both the parent period and its elapsed fraction matter.
At a glance
- Parent
- Mahadasha
- Child
- Antardasha
- Duration formula
- Full parent years × subperiod ruler years ÷ 120
- Subperiod order
- Start with the parent ruler, then follow the cycle
What does the second planet in a dasha label mean?
In Venus/Sun, Venus rules the main period and Sun rules its subperiod. The notation does not assert a conjunction, an aspect or two main periods running at once. Preserve the hierarchy when comparing a report with its timeline.
Antardashas begin with the mahadasha ruler and continue through the cyclic order. The order inside a Venus period therefore differs from the order inside a Sun period, even though both contain all nine rulers. Deeper subdivisions apply the same proportional principle recursively.
Equal durations do not mean identical periods
Venus/Sun lasts 20 × 6 / 120 = 1 model year. Sun/Venus also lasts 6 × 20 / 120 = 1 model year, but its parent and sequence position are different. Reversing the labels preserves this multiplication, not the timeline context.
Within Venus mahadasha, Venus/Venus comes first and lasts 20 × 20 / 120 = 10/3 model years. Venus/Sun follows it. Compare these full intervals before translating them into dates under a stated year-length convention.
Does the antardasha sequence restart at birth?
No. The first displayed mahadasha may have begun before birth. Construct its full subperiod sequence, locate the birth instant within it, and show the remaining tail. Dividing only the leftover mahadasha balance as if it were a new complete parent gives the wrong boundaries.
An uncertain Moon longitude or birth timestamp can place birth or the target date on either side of a subperiod boundary. Keep that ambiguity visible rather than selecting the more appealing reading. The current-dasha guide provides a worked lookup without claiming that a subperiod causes an event.
Sources and editorial basis
- P. V. R. Narasimha Rao: Vedic Astrology — An Integrated ApproachRao, Vedic Astrology: An Integrated Approach. §16.3, p. 212: nine proportional antardashas beginning with the parent ruler; §16.2, pp. 210–211: birth balance. Reconstructing the full parent before locating birth is an editorial derivation of these two rules. These passages document named traditional methods, not scientific validity. Examples are synthetic, not verified birth observations.A named practitioner’s introduction to Jyotish. Used for terminology and a stated method, not universal school agreement or scientific validation. The added March 18, 2010 note describes changed views; it does not establish a fully revised 2010 edition.
- OpenFate Editorial MethodologyOpenFate Editorial Methodology, stable sections #editorial-principles, #editorial-workflow, #editorial-ai, and #editorial-context. Used for the calculation/interpretation and evidence-boundary policy.OpenFate separates deterministic chart calculation, traditional interpretation, and modern editorial explanation.
- OpenFate Vedic implementation: local source review, 2026-09-08Read-only source review on 2026-09-08: openfate/app/modules/vedic/logic/policy.ts, VEDIC_ENGINE_POLICY (vedic-policy-1.1.0): Vimshottari only and 365.25-day years; math.ts, horaSign and computeVargaSigns: named D2 Sun/Leo and Moon/Cancer mapping plus D6/D9/D10/D24. This verifies the local declared implementation, not current production or alternate-method UI support.An editorial review of local policy and calculation source files, not an independently accessible publication or proof of the deployed version. Implementation limitations and discrepancies remain separate from traditional arithmetic.