Glasgow Coma Scale (GCS) Calculator
Glasgow Coma Scale (GCS) Calculator
Score eye opening, verbal and motor response on the 2014 criteria, and read the components as well as the total. The lowest possible total is 3 and never 0, and an untestable component is NT rather than 1.
Glasgow Coma Scale
Three components, 3 to 15Eyes open to finger-tip pressure, groaning with no words, rapid withdrawal of the right arm
Scoring
Minimum 3 · maximum 15 · severe 3–8 · moderate 9–12 · mild 13–15
- the minimum is 3
- every component scores 1 for no response, so a GCS of 0, 1 or 2 does not exist. Where one is recorded it almost always means an untestable component was entered as a nought
- NT is not 1
- record a component as Not Testable where an interfering factor prevents assessment, and report no total: “Do not report a total score when a component is Not Testable because the score will be low and this could be confusing to medical colleagues.” Intubation, sedation, paralysis, periorbital swelling and no shared language are the usual reasons
- best limb, and the order of assessment
- each component is assigned “according to highest response observed”, right and left checked separately, and the published order is check, observe, stimulate, rate — observe spontaneous behaviour before applying finger-tip, trapezius or supraorbital pressure
- licence and attribution
- The Glasgow Coma Scale is copyright of the University of Glasgow, free for clinical care and research with no licence required, provided the copyright is acknowledged. It is acknowledged here. First published by Teasdale and Jennett in the Lancet in 1974; these are the 2014 criteria
Worked example
Eyes open to finger-tip pressure, groaning with no words, rapid withdrawal of the right arm
To pressure = E2 · sounds only = V2 · normal flexion = M4
2 + 2 + 4 = 8 points, in the severe stratum of 3 to 8
Hand it over as E2 V2 M4, total 8. A bare “GCS 8” is equally consistent with E1 V1 M6 — a patient obeying commands — and those are not the same clinical problem
Change the motor response to extension and the total falls to 6; to obeying commands and it rises to 10, crossing into the moderate stratum
Now suppose the patient is intubated. The verbal component is NT, not 1, and this page returns no total. 2 + NT + 4 is not 6, and reporting 6 would understate responsiveness by at least one point and possibly four
The three components
| Component | Criteria, highest response to lowest | Range |
|---|---|---|
| Eye opening (E) | Spontaneous · To sound · To pressure · None | 4 to 1 |
| Verbal response (V) | Orientated · Confused · Words · Sounds · None | 5 to 1 |
| Motor response (M) | Obeys commands · Localising · Normal flexion · Abnormal flexion · Extension · None | 6 to 1 |
Severity strata, and the one place the sources disagree
| Total | Stratum | Source |
|---|---|---|
| 13 to 15 | Mild | glasgowcomascale.org FAQ |
| 9 to 12 | Moderate | glasgowcomascale.org FAQ |
| 3 to 8 | Severe | Implemented here. The same FAQ writes this stratum as a sum score under 8, which leaves a total of exactly 8 in no stratum |
Three components, one number, and what the number throws away
The scale describes responsiveness in three dimensions: whether the eyes open, whether speech is organised, and what the limbs do. Each is scored against defined criteria — four grades for eye opening, five for verbal, six for motor — and the lowest grade in each is 1, for no response. That is why the lowest possible total is 3. A GCS of 0 is not a very low score; it is not a score at all, and a reported 0, 1 or 2 almost always means something untestable was entered as a nought.
The summed score came after the scale and was always a compromise. The scale’s own site puts it bluntly: the composite “lost some of the detail and discrimination conveyed by the full scale”. Two patients at a total of 8 can be E1 V1 M6, obeying commands with closed eyes and no speech, or E2 V2 M4, opening to pressure and withdrawing but following nothing — different lesions, different trajectories, one number. The same applies to the untestable component: an intubated patient has no verbal score, and the published guidance is to record NT and report no total, because a missing component scored as 1 gives a figure that is systematically low and looks exactly like deterioration. This calculator therefore refuses to sum when any component is NT.
Two habits account for most disagreement between examiners. The motor score is the best response from any limb, with right and left checked separately and asymmetry recorded as a focal deficit rather than folded into the score — scoring the hemiplegic side reliably makes a patient look worse than they are. And the order matters: check for interfering factors, observe spontaneous behaviour, stimulate only where nothing spontaneous appears, then rate. Observing before stimulating separates a patient who was already localising from one who needed a trapezius pinch to do it. The Glasgow Coma Scale is copyright of the University of Glasgow, free for clinical care and research with no licence required, provided the copyright is acknowledged. It is acknowledged here. A grade is not a diagnosis and a cohort risk is not this patient’s probability: a stratum in which 72 per cent died tells you about that cohort, not which 72 per cent. Every threshold here comes from a named cohort, and cohorts differ in case mix, era and treatment; where your unit’s protocol differs, it takes precedence.
Frequently asked questions
What is the lowest possible Glasgow Coma Scale score?
Three. Each component scores 1 for no response, so 3 is the floor. A GCS of 0, 1 or 2 usually means an untestable component was recorded as a nought.
How do I score the GCS in an intubated patient?
You do not score the verbal component. Record it as NT and report the two components that were testable; the published guidance is not to report a total when a component is NT, “because the score will be low and this could be confusing to medical colleagues”.
Which limb gives the motor score?
The best-responding one, with right and left checked separately and asymmetry recorded as a focal deficit alongside the score rather than inside it.
Is the Glasgow Coma Scale copyrighted, and can I reproduce it?
It is copyright of the University of Glasgow, administered through glasgowcomascale.org. That site states the materials “may all be used for clinical care and clinical research at no cost. No license is required”, provided the copyright is acknowledged.
What counts as a severe GCS?
The scale’s own FAQ gives mild as 13 to 15, moderate as 9 to 12 and severe as a sum score under 8 — wording that leaves exactly 8 unassigned. Almost every other use treats 3 to 8 as severe, which is what this page implements.
Related calculators
References
- Royal College of Physicians and Surgeons of Glasgow / University of Glasgow. Glasgow Coma Scale: permissions. glasgowcomascale.org/permissions (accessed 7 October 2026).
- Royal College of Physicians and Surgeons of Glasgow. Glasgow Coma Scale: frequently asked questions; What is the Glasgow Coma Scale? glasgowcomascale.org (accessed 7 October 2026).
- Teasdale G. Glasgow Coma Scale assessment aid. glasgowcomascale.org (accessed 7 October 2026).
- MSD Manual Professional Edition. Glasgow Coma Scale. Rahway, NJ: Merck & Co.
Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/