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GCS Calculator (Glasgow Coma Scale)

Table of contents

What is the Glasgow Coma Scale?When to use the GCSHow to use the Glasgow Coma Scale calculatorInterpretation of GCS scoreControversy surrounding the GCS

Welcome to the GCS calculator or Glasgow Coma Scale calculator. The Glasgow Coma Scale is one of the most important and fundamental scales in medicine, used by almost every doctor to estimate a patient's consciousness. Thanks to our GCS calculator, you can also calculate the GCS score in just three simple steps!

Check out our other calculators with essential medical scales, such as the Apgar score or the MELD score!

What is the Glasgow Coma Scale?

In 1974, Graham Teasdale and Bryan J. Jennett, professors of neurosurgery at the University of Glasgow, published an article in The Lancet — one of the most influential medical journals — in which they described and proposed a new scale to assess coma and state of consciousness. Since then, due to its simplicity and feasibility, it has become an incredibly popular tool.

Moreover, the GCS score is used as a part of other medical scales and scoring systems, such as Revised Trauma Score and APACHE II (see Revised Trauma Score calculator and APACHE II calculator).

When to use the GCS

Initially, Teasdale and Jennett developed the Glasgow Coma Scale as an approach to the serial assessment of patients with traumatic brain injury. Nowadays, doctors of nearly all specialties use it in their medical wards. You should calculate GCS:

  • After any major trauma;
  • In lost consciousness;
  • In suspicion of decortication or decerebration;
  • In patients in a coma; and
  • In all patients in intensive care units.

How to use the Glasgow Coma Scale calculator

Let's show you how to use the GCS calculator. The GCS consists of 3 tests:

  • Eye response (E4);
  • Verbal response (V5); and
  • Motor response (M6).

You can get from 1 to 4, 5, or 6 points out of each test. The sum of the values of the test is a GCS score.


Eye response

Verbal response

Motor response


Does not open eyes

Makes no sounds

Makes no movements


Opens eyes in response to pain

Makes sounds

Extension to painful stimuli


Opens eyes in response to voice


Abnormal flexion to painful stimuli


Opens eyes spontaneously

Confused, disoriented

Flexion / Withdrawal to painful stimuli



Oriented, converses normally

Localizes to painful stimuli




Obeys commands

Let's look at the example!

Adult male after brain injury opens their eyes when you speak to them and can hold a conversation, though they seem disoriented. Patient flexes elbow and wrist when you put pressure on the nail bed.

Such a patient receives 3 points for eye response, 4 points for verbal response, and 3 points for motor response. GCS score = 10 pts.

Interpretation of GCS score

The lowest possible GCS score is 3, and the highest is 15 points. The Glasgow Coma Scale enables us to divide brain injuries into the following categories:

  • Minor (GCS 13-15);
  • Moderate (GCS 9-12); and
  • Severe (GCS 3-8).

A GCS of 8 or less indicates the need to intubate a patient (placed on a ventilator).

Controversy surrounding the GCS

GCS was not originally intended to be converted into a single score. Moreover, some researchers take issue with the scale's poor inter-rater reliability and lack of prognostic utility.

It is worth noticing that the same GCS score will predict different mortality depending on the components. For example, a GCS of 4 with the components 1 + 1 + 2 (Eye + Verbal + Motor) predicts a mortality rate of 48%. On the other hand, a GCS of 4 with individual scores 2 + 1 + 1 predicts a mortality rate of 19%.

Nevertheless, the GCS is a routine and widespread test that remains a standard of care in many clinical situations.

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