Glasgow Coma Scale Calculator

Glasgow Coma Scale scoring

Assess the patient’s best response in each of the three domains and take the highest score they achieve. Add the three responses only when every component is testable.

NICE expects all communication and records to describe the three separate responses alongside the total — for example E4, V4, M5 (GCS 13 out of 15). If any component is NT, record the remaining components but do not report a total.

GCS score interpretation

The total grades the severity of impaired consciousness after head injury. Severity bands guide urgency; they do not replace the full head injury assessment.

• 13–15Mild head injury range

  Assess against head injury criteria. A GCS of 15 does not exclude significant injury — imaging and admission decisions depend on the full risk factor set.

• 9–12Moderate head injury range

  Urgent clinical assessment and close monitoring for deterioration. In the emergency department a GCS of 12 or less on initial assessment is an indication for CT within 1 hour.

• 3–8Severe head injury

  Urgently assess the airway and escalate through the appropriate major trauma pathway. Airway management and transfer decisions require trained clinical judgement.

Bands are from NICE NG232: mild traumatic brain injury is a GCS of 13–15, moderate is 9–12, and severe is 8 or less.

How to calculate the Glasgow Coma Scale

1. 1Check for reversible causes of reduced consciousness and establish the pre-injury baseline if possible.
2. 2Score eye opening: spontaneous scores 4; open to sound 3; open only to pressure 2; none 1.
3. 3Score the verbal response against the descriptors above, from orientated (5) to none (1).
4. 4Score the motor response to command, then to a painful stimulus if needed, from obeying commands (6) to none (1).
5. 5Add the three responses, record them individually (for example E3, V4, M5) with the total out of 15, and repeat the assessment — trends matter more than any single score.

Common pitfalls

• Passing on only the total. NICE requires the three component scores to accompany every recorded or handed-over total, because E3, V4, M6 and E1, V2, M6 are different patients with the same number.
• Scoring an unassessable component as its minimum anyway. If swelling, intubation or a pre-existing deficit makes a domain untestable, record what was assessed and mark the rest as untestable rather than inventing a score.
• Assuming a baseline GCS of 15. People with dementia or other chronic neurological conditions may run lower — establish their usual baseline and interpret changes against it.
• Using a normal GCS to exclude brain injury. Imaging decisions in NICE NG232 combine the GCS with loss of consciousness, amnesia, mechanism, vomiting and anticoagulant use, among other risk factors.
• Using the adult scale in preverbal children. The paediatric version substitutes a grimace alternative for the verbal score, so totals are not interchangeable.

Frequently asked questions

What is a normal Glasgow Coma Scale score?

A fully alert adult scores 15 out of 15 — spontaneous eye opening (E4), orientated speech (V5) and obeying commands (M6). A score of 15 does not by itself exclude a head injury; assessment follows the full risk factor set in NICE NG232.

What does a GCS of 8 or less mean?

It falls within the severe traumatic brain injury band and signals that the airway is at risk, which is why patients with a GCS of 8 or less need urgent airway assessment and major trauma pathway activation. It is sometimes summarised as "GCS 8, intubate", but the decision belongs to the clinician managing the airway, not the score alone.

Why record E, V and M separately instead of just the total?

Because the total hides which domain is affected. NICE NG232 requires the individual components to be described in all communications and every patient record so that colleagues can detect deterioration in a specific domain between assessments.

How is the GCS used in NEWS2 and sepsis screening?

NEWS2 scores new confusion or a reduced level of consciousness (the C in ACVPU) as 3 points, and qSOFA counts altered mentation — commonly a GCS below 15 — as one of its three criteria. The scales complement each other rather than replace one another.

Does the GCS diagnose brain injury?

No. It grades the degree of impaired consciousness and supports monitoring and escalation decisions. Diagnosis and imaging decisions require the full clinical assessment described in NICE NG232.

Sources and further reading

• Head injury: assessment and early management (NG232) — NICE
• Teasdale G, Jennett B. Assessment of coma and impaired consciousness. A practical scale. Lancet 1974;2(7872):81–4 — PubMed
• Glasgow Coma Scale: dealing with untestable components — Institute of Neurological Sciences, NHS Greater Glasgow and Clyde

This page is reference information for registered healthcare professionals. It is not medical advice and does not replace clinical judgement, local policy, or the current version of the source guidance. Always verify scores and thresholds against your own organisation's pathway before acting on them.