The Glasgow Coma Scale (GCS) is calculated by adding together three separate scores: one for eye opening (1 to 4 points), one for verbal response (1 to 5 points), and one for motor response (1 to 6 points). The total ranges from 3 (deepest unresponsiveness) to 15 (fully alert and oriented). Each component tests a different level of brain function, and the combined number gives a quick snapshot of how conscious a person is after a head injury or other neurological event.
The Three Components
Every GCS assessment evaluates the same three things in order: whether the person opens their eyes, whether they can speak coherently, and how well they move. You test each one separately, assign the highest response the person demonstrates, then add the three numbers together.
Eye Opening (E): 1 to 4 Points
- 4 points: Eyes open spontaneously, without any prompt.
- 3 points: Eyes open in response to speech or a verbal command.
- 2 points: Eyes open only in response to a painful stimulus, like pressing firmly on a fingernail bed.
- 1 point: No eye opening at all, even with pain.
If the person’s eyes are swollen shut from facial injuries, the eye component can’t be tested reliably. In that case, it’s recorded as “not testable” (NT) rather than scored as a 1.
Verbal Response (V): 1 to 5 Points
- 5 points: Oriented. The person knows who they are, where they are, and roughly what time or date it is.
- 4 points: Confused. They can form sentences and carry on a conversation, but their answers are wrong or muddled.
- 3 points: Inappropriate words. They say recognizable words, but not in a way that makes conversational sense.
- 2 points: Incomprehensible sounds. They moan or groan but produce no actual words.
- 1 point: No verbal response at all.
If someone has a breathing tube or tracheostomy in place, the verbal score is recorded as NT. You can still calculate and report the eye and motor scores individually.
Motor Response (M): 1 to 6 Points
- 6 points: Obeys commands. Ask the person to hold up two fingers or squeeze your hand, and they do it correctly.
- 5 points: Localizes pain. When a painful stimulus is applied, they reach toward it purposefully, trying to push it away.
- 4 points: Withdrawal. They pull the limb away from the painful stimulus, but without a purposeful reaching motion.
- 3 points: Abnormal flexion. The arms bend inward toward the body in a stiff, stereotyped posture (sometimes called decorticate posturing).
- 2 points: Extension. The arms straighten and rotate inward in response to pain (sometimes called decerebrate posturing). This indicates deeper brain dysfunction than flexion.
- 1 point: No motor response at all.
The motor component carries the most diagnostic weight of the three. In situations where only one score can be assessed, the motor response alone is a reasonably strong predictor of outcome.
How to Add Up the Score
The formula is straightforward: E + V + M = GCS total. A person who opens their eyes spontaneously (4), speaks but is confused (4), and obeys commands (6) scores a 14. Someone with no eye opening (1), incomprehensible sounds (2), and abnormal flexion (3) scores a 6.
Always record the component scores alongside the total, not just the total by itself. Writing “GCS 9” tells you far less than “E3 V2 M4,” because two patients can land on the same total with very different underlying patterns. A person scoring E2 V4 M3 and another scoring E3 V2 M4 both have a GCS of 9, but their clinical pictures look quite different.
When testing, always record the best response you observe. If the right arm obeys commands but the left arm only withdraws, the motor score is 6, not 4. The idea is to capture the highest level of brain function still intact.
What the Scores Mean
For traumatic brain injury, the total GCS is grouped into three severity categories:
- Mild (13 to 15): The person is largely alert and conversational. Most concussions fall into this range.
- Moderate (9 to 12): Consciousness is impaired but not absent. The person may be confused, drowsy, or only partially responsive.
- Severe (3 to 8): The person is comatose or near-comatose. A GCS of 8 or below is the traditional threshold at which clinicians consider protecting the airway with intubation.
A score of 15 is normal. A score of 3 is the lowest possible, not zero, because each component has a minimum of 1 point even when there’s no response at all.
Scoring for Infants and Young Children
Children younger than about 2 years old can’t follow verbal commands the same way adults can, so the GCS uses a modified version for preverbal patients. The eye opening scale stays the same, but the verbal and motor responses are adapted to match developmental expectations.
For verbal response, the modified scale looks for age-appropriate behaviors: cooing and babbling earns 5 points, irritable crying earns 4, crying only in response to pain earns 3, moaning to pain earns 2, and no vocalization earns 1. For motor response, spontaneous purposeful movement earns 6 points, withdrawing from touch earns 5, withdrawal only with pain earns 4, abnormal flexion earns 3, extension earns 2, and no movement earns 1.
The total still ranges from 3 to 15, and the same severity categories apply. The difference is purely in what behaviors count at each level.
Common Pitfalls That Skew the Score
Several situations can make a GCS unreliable if you’re not aware of them. Alcohol or sedating medications can lower verbal and motor scores without any actual brain injury. Facial swelling, intubation, or a language barrier can make one or more components impossible to assess. In all these cases, noting what couldn’t be tested (and why) matters more than forcing a number.
Timing also matters. A single GCS score is a snapshot. Repeated assessments over time are more valuable than any one reading, because a declining score signals worsening brain function even when the absolute number still looks moderate. A drop of 2 or more points from one assessment to the next is a red flag, regardless of where the score started.
Finally, the GCS was designed specifically for traumatic brain injury. It’s widely used for other causes of altered consciousness (strokes, overdoses, infections), but the severity categories of mild, moderate, and severe were validated for trauma patients. Interpreting the score in non-trauma contexts requires some caution.