Why longevity is different
Longevity is the one topic where the harm of being wrong — or right — is so great, and the technique so uncertain, that restraint is the rule, not a preference. The classics offer elaborate lifespan mathematics, and reading ABOUT them is fair scholarship; USING them to hand a client or family a number is not. The prohibition on death and lifespan prediction is the firmest line in the art (enshrined in the ethics lesson, n112).
Studying the ayurdaya methods is scholarship; pronouncing a lifespan from them is the line you never cross.
The bands
Alpayu, madhyayu, purnayu
The rough frame: alpayu (short life, up to ~32), madhyayu (middle, ~32–70), purnayu (full, ~70–100), with divyayu beyond. Classically the band is judged from combinations of the lagna, the 8th house, and Saturn, cross-checked in threes. Even this coarse three-way sorting is applied cautiously — a BAND of decades, never a date, and only ever as one input.
The bands sort a life into short/middle/full — decades wide, and still held loosely.
Two methods
Pindayu and Amsayu
Two real ayurdaya procedures. PINDAYU sums each planet's contributed years (a fixed maximum per graha, scaled by its dignity and position), then applies reductions — for combustion, enemy signs, being overcome by malefics, and more. AMSAYU derives the span from the lagna's and planets' precise longitudes via the navamsha. Both are elaborate; both are classical; and they routinely disagree.
Pindayu counts contributed years with reductions; Amsayu reads spans from longitude — two different engines.
Worked · Priya (illustrative)
The methods disagree
Run both on Priya as a demonstration. Pindayu, after its reductions, lands near 76 years; Amsayu, from the longitudes, lands near 61 — a gap of fifteen years on ONE chart. (These figures are constructed to illustrate the disagreement, not computed from her actual placements.) That spread is the entire argument: when two canonical methods differ by a decade and a half, no single number deserves a client's trust.
Pindayu ~76 vs Amsayu ~61 (illustrative): a 15-year gap that discredits any confident lifespan claim.
What professionals actually use
The marakas and the 8th — qualitatively
Instead of a number, working astrologers hold a qualitative map: the 8th house is longevity's own house (ayus); the 2nd and 7th are maraka (death-inflicting) houses, their lords maraka planets. Their dashas, and hard transits over sensitive points, flag VULNERABLE PERIODS — times to counsel care, rest, and check-ups. Never a death date; only seasons to be attentive, delivered without fear.
A maraka dasha flags a period to prioritise health and caution — a vulnerable season, never an end date.
The one idea to keep
Restraint, proven not asserted
Longevity is the domain of restraint — and the restraint is earned: two classical methods disagree by years on a single chart. Hold the alpayu/madhyayu/purnayu bands as a coarse frame and the marakas/8th as a qualitative map of vulnerable periods, and NEVER predict death or lifespan. The refusal, warmly delivered, is the reading (n112).