In Jain Dharma, āyuṣya karma is the karma that determines the span of life for a soul in a particular birth.

How is āyuṣya karma determined?

According to Jain philosophy, āyuṣya karma is bound at the end of the previous life, especially during the final moments of that life, based on:

• the state of the soul
• its passions like anger, pride, deceit, and greed
• its merit and demerit
• the kind of mental disposition present near death
• the overall karmic bondage accumulated in that life

This āyuṣya karma then decides:

• which gati the soul will take birth in,
• and how long that life will last in that birth.

Why do some people die at a young age and some live to 100?

In Jain view, this difference happens because each soul carries different karmic bondage.

So:

• a soul with short-life āyuṣya karma will die earlier,
• a soul with long-life āyuṣya karma will live longer.

It is not only visible effort, health, or external conditions that decide life span. These are nimitta (supporting causes), but the main cause is the soul’s own bound āyuṣya karma.

Important Jain understanding

Jainism teaches that life span is already fixed once āyuṣya karma is bound. During that birth, the soul may experience many conditions—health, sickness, accidents, or age—but the actual time of departure happens when that āyuṣya karma gets exhausted.

In simple words

• Who dies at what age is decided by karmic bondage
• Not everyone gets the same life span
• The soul’s past conduct and death-time disposition play a major role in binding āyuṣya karma

If you want, I can also explain the four types of āyuṣya karma in Jainism.