Longevity (āyur, āyus) is the most ethically loaded computation in jyotiṣa. The classical tradition is unanimous that āyur is one of the hardest things to determine with confidence, and that even when the computation suggests a short āyu, multiple bhaṅga-yogas (cancellation patterns) may intervene. Phaladīpikā Ch. 16 gives the three standard methods: piṇḍāyu adds contributions from each graha based on position; aṃśāyu uses the navāṃśa-fraction of each graha; naisargikāyu assigns a fixed lifespan-contribution per graha.
The three āyur-khaṇḍas (lifespan-classes) are alpa (0–32 years), madhya (32–64), and dīrgha (64+, sometimes extended to 100+ as pūrṇa-dīrgha). Different lagna-lord and 8th-lord positions place the nativity in one of these classes; the three methods then refine within the class. Pārāśara's BPHS Ch. 88 and Jaimini's distinct method (Jaimini-sūtras Adhy. 3 · Pāda 3) provide cross-checks.
We compute none of this for you on the public engine — and not for marketing reasons. Longevity-determination is the textbook example of a calculation where śāstric outputs require an experienced ācārya's interpretation, NOT a mechanical reading. This module exists so you understand the tradition's approach; the interpretive judgment belongs to the qualified jyotiṣī.