Calculate the APACHE II severity score from admission physiology, age and chronic health — with an approximate mortality band for context.
Result
How to use this tool
Use the most abnormal value for each measure in the first day of intensive care.
Give FiO2 and PaO2; the tool switches to the gradient rule at FiO2 ≥ 0.5.
GCS contributes 15 minus the score; age adds 0–6 points.
0 with no chronic failure, 2 for elective postoperative cases with chronic disease, 5 for non-operative or emergency cases.
Formula & worked example
All values normal, GCS 15, age 40, no chronic points gives a low score near 0; a temperature of 40°C, heart rate 150 and GCS 8 push the total well into the high teens or above.
Limitations — read this before you rely on it
Educational aid only, using the published APACHE II scoring tables. It is not medical advice, not a diagnosis or prognosis, and does not replace intensive-care clinical judgement. Use worst first-24-hour values; scores from incomplete or non-ICU data are not valid APACHE II scores.
Frequently asked questions
A severity-of-illness score for intensive-care patients, combining 12 physiology measures, age and chronic health, scored 0–71. Higher means sicker on admission.
Each measure is scored 0–4 from the published table using the worst value in the first 24 hours of ICU admission, then GCS contributes 15 minus the GCS.
An approximate published population mortality for that score band. It is not a personal prognosis — diagnosis, treatment and trajectory matter far more.
At FiO2 of 0.5 or more the table uses the alveolar–arterial gradient; below 0.5 it uses PaO2 alone. This tool follows that published rule.
Only as an educational aid. APACHE II was designed and validated for ICU admission scoring, not for ward or home use.