APACHE II Score Calculator

APACHE II Score Calculator for Critical Care. Use APACHE II for severity adjustment and population-level risk discussions, not as a sole bedside treatment decision tool.

How this calculator works

APACHE II estimates ICU severity of illness using acute physiology variables, age, and chronic health points.

Inputs used

  • Physiology variables
  • Age
  • Chronic health status

Clinical interpretation

Use APACHE II for severity adjustment and population-level risk discussions, not as a sole bedside treatment decision tool.

Limitations and safety notes

Performance varies by population and era. Do not use for individual prognostic certainty or treatment limitation decisions.

References

  • Knaus WA, Draper EA, Wagner DP, Zimmerman JE. APACHE II: a severity of disease classification system. Crit Care Med. 1985.

Editorial review and citation methodology

Reviewed by the Quick Medical Calculator Editorial Team. Last reviewed: June 19, 2026. The review checks calculator inputs, intended population, interpretation, limitations, and source alignment.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.