GCS Calculator

What the Glasgow Coma Scale measures

The Glasgow Coma Scale (GCS) is a way of describing how awake and responsive someone is, using three things you can observe: whether they open their eyes, what they say, and how they move. Each is scored separately, and the three add up to a total between 3 and 15. A score of 3 is the lowest possible - it does not mean zero, because the minimum in each component is 1. A score of 15 is fully alert and orientated.

Always record the three parts, not just the total. E3V4M5 and E4V3M5 both add up to 12, but they describe different patients, and the motor score in particular carries most of the predictive weight. Writing the total alone throws that information away.

Score the best response the patient gives in each component. If one side of the body moves better than the other, use the better side. If something prevents you scoring a component at all - an intubated patient cannot speak, a swollen eye cannot open - record it as not testable rather than guessing a number.

Score a patient

What each response scores

What the total means

These bands are the conventional way of describing traumatic brain injury severity. They are a description of how the patient presents, not a decision rule on their own - a patient with a reassuring total who is deteriorating matters far more than the number.

Where the GCS is weakest

• The verbal score in an intubated patient. Someone with a tube in place cannot speak. Record the verbal component as not testable rather than scoring it 1, which would understate their true conscious level.
• Young children. A pre-verbal child cannot be scored on the adult verbal scale. A paediatric version of the scale substitutes age-appropriate responses.
• Anything that clouds the picture. Alcohol, drugs, hypoglycaemia, hypoxia and postictal states all lower the GCS without a brain injury being present. Check a blood glucose in every patient with a reduced conscious level.
• Between-observer variation. Different clinicians scoring the same patient do not always agree, particularly on the middle motor responses. The trend recorded by one assessor is more reliable than a single number passed between several.