Omni Calculator logo

Injury Severity Score Calculator

Created by Joanna Michałowska, PhD candidate
Reviewed by Dominik Czernia, PhD, Jack Bowater and Łucja Zaborowska, MD, PhD candidate
Based on research by
Bolorunduro OB, Villegas C, Oyetunji TA, Haut ER, Stevens KA, Chang DC, Cornwell EE 3rd, Efron DT, Haider AH. Validating the Injury Severity Score (ISS) in different populations: ISS predicts mortality better among Hispanics and females.; Journal of Surgical Research; March 2011See 1 more source
Baker SP, O'Neill B, Haddon W Jr, Long WB The injury severity score: a method for describing patients with multiple injuries and evaluating emergency care.; J Trauma.; March 1974
Last updated: Jun 05, 2023

The Injury Severity Score calculator helps to assess trauma severity, especially in patients with multiple injuries. It helps to define the term "major trauma" and ISS correlates with mortality, morbidity, and hospitalization time after injury. Read the text below to find out more about the Injury Severity Score calculation (ISS score trauma) and interpretation.

If you are interested in calculators that assess the severity of other medical conditions, check out the revised trauma score calculator, SOFA score calculator and SAPS II calculator calculators.

We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace professional medical advice.

Injury severity score

Baker and colleagues created the Injury Severity Score in 1974. This medical score is based on the previously developed Abbreviated Injury Scale (AIS) and takes into account the three (out of six) most severe system injuries.

This adjustment allows doctors to add increasing weight to the most severe injuries. According to the study's results, injuries that alone may not be life-threatening can significantly influence mortality when combined with other trauma.

Injury Severity Score calculation

In this paragraph, you will find information on how to calculate Injury Severity Score.

Trauma in the ISS score can be related to six regions of the human body:

  1. Head and neck (includes cervical spine);
  2. Face: facial skeleton, nose, mouth, eyes, and ears;
  3. Chest: thoracic spine and diaphragm;
  4. Abdomen: abdominal organs and lumbar spine (includes pelvic contents);
  5. Extremities or pelvic girdle: pelvic skeleton; and
  6. External

Each part of the body is then scored for the worst injury as follows:



No injury














After scoring each body system, we perform the injury severity score calculation according to the following rules:

  1. Choose the three most severely injured body systems.
  2. Perform Injury Severity Score calculation by adding the three highest squared scores :
ISS=highest12+highest22+highest32\footnotesize \mathrm{ISS} = \mathrm{highest}_1^2+\mathrm{highest}_2^2+\mathrm{highest}_3^2

If any body system has a score of 6, ISS is automatically set to have the highest value - 7575 points.

ISS score trauma interpretation

Now that you know how to calculate Injury Severity Score, let's take a look at its interpretation:

  • Injury Severity Score (ISS) takes values from 00 to 7575 points;

  • ISS score is the only anatomical scoring system that correlates linearly with mortality, morbidity, hospitalization time, and other severity measures;

  • We associate ISS score >15> 15 with major trauma; and

  • Bolorunduro et al. proposed the following classification of the injuries:





99 - 1515


1616 - 2424



Very severe/profound

Injury Severity Score calculator - a practical example

It would help you check you know how to calculate Injury Severity Score if we used a practical example of a patient who has been in a car crash. Doctors graded his injuries as follows:

Worst injury in the region


Head and neck

No injury (00 points)


Minor (11 points)


Moderate (22 points)


Serious (33 points)


No injury (00 points)


No injury (00 points)

First, we need to find the regions with the highest score. In this example, those are:

  1. Abdomen - 33 points
  2. Chest - 22 points
  3. Face - 11 point

Now we can calculate the patient's Injury Severity Score (ISS score trauma) as follows:

ISS=highest12+highest22+highest32=32+22+12=9+4+1=14\footnotesize \begin{split} \mathrm{ISS} & = \mathrm{highest}_1^2+\mathrm{highest}_2^2+\mathrm{highest}_3^2\\ &=3^2+2^2+1^2\\ &=9+4+1\\ &=14 \end{split}

This patient's injuries can be categorized as moderate. The forces involved in the car crash were, for sure, not risible: you can learn how to calcualte them with our car crash calculator.

Joanna Michałowska, PhD candidate
Worst injury in the area:
Head and neck
No injury
No injury
No injury
No injury
No injury
No injury
Injury Severity Score
An Injury Severity Score of less than 9 can be classified as minor trauma.
Check out 14 similar intensive & emergency care calculators 🚑
Alvarado scoreAPACHE IIGlasgow coma scale… 11 more
People also viewed…


The APFT calculator finds the Army Physical Fitness Test score.

Black Friday

How to get best deals on Black Friday? The struggle is real, let us help you with this Black Friday calculator!

Christmas tree

Welcome to the Christmas tree calculator, where you will find out how to decorate your Christmas tree in the best way. Take a look at the perfect Christmas tree formula prepared by math professors and improved by physicists. Plan in advance how many lights and decorations you'll need!


The DRI calculator will show you your daily recommended intake of vitamins, macronutrients and micronutrients.
Copyright by Omni Calculator sp. z o.o.
Privacy, Cookies & Terms of Service