The ISS is the standard measure of overall injury severity in trauma systems. An ISS above 15 defines major trauma and is associated with a mortality of about 10%.
How to use the Injury Severity Score Calculator
- Head or neck – highest AIS
- Face – highest AIS
- Chest – highest AIS
- Abdomen or pelvic contents – highest AIS
- Extremities or pelvic girdle – highest AIS
- External (skin) – highest AIS
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the highest AIS (0 none, 1 minor, 2 moderate, 3 serious, 4 severe, 5 critical, 6 unsurvivable) for each region.
Inputs explained
| Field | What to enter |
|---|---|
| Head or neck – highest AIS | A number |
| Face – highest AIS | A number |
| Chest – highest AIS | A number |
| Abdomen or pelvic contents – highest AIS | A number |
| Extremities or pelvic girdle – highest AIS | A number |
| External (skin) – highest AIS | A number |
Example values
How the main result changes when Head or neck – highest AIS changes and everything else stays at the example values above:
| Head or neck – highest AIS | Injury severity score (/ 75) |
|---|---|
| 1.5 | 15 |
| 2.25 | 18 |
| 3 | 22 |
| 3.75 | 27 |
| 4.5 | 33 |
| 6 | 75 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
ISS = A² + B² + C² (the three highest AIS scores in different body regions)
Any AIS of 6 gives ISS 75
Major trauma: ISS > 15
Worked example
Inputs — Head or neck – highest AIS: 3; Face – highest AIS: 1; Chest – highest AIS: 2; Abdomen or pelvic contents – highest AIS: 0; Extremities or pelvic girdle – highest AIS: 3; External (skin) – highest AIS: 1.
Results — Injury severity score = 22 / 75; Severity = Serious – major trauma (16–24).
Key terms
- AIS
- Abbreviated Injury Scale.
Frequently asked questions
What ISS defines major trauma?
An ISS greater than 15.
Why are scores squared?
Mortality rises non-linearly with injury severity.
What is the New ISS?
NISS uses the three most severe injuries regardless of body region.