NIH Stroke Scale (NIHSS) Calculator — Full 15-Item Scale and the Published Shortened Versions

Background.

There is no such instrument as a generic "simplified NIH Stroke Scale", so this page does not pretend otherwise. It implements the full 15-item NIH Stroke Scale as its default, and offers the two shortened scales that genuinely exist in the literature: the sNIHSS-8 and sNIHSS-5 of Tirschwell and colleagues, published in Stroke in 2002. Inventing an abbreviation would have produced a number with nothing behind it. This is a clinical aid for clinicians; it measures deficit, it is not a diagnosis of stroke, and it does not predict outcome for an individual patient.

The full scale has fifteen items, not eleven, because three of the numbered items split in two. Level of consciousness is scored three times — alertness as 1a, orientation questions as 1b, and command-following as 1c — and the motor items are scored separately for the left and right arm and the left and right leg. Adding the item maxima gives 3 + 2 + 2 + 2 + 3 + 3 + 4 + 4 + 4 + 4 + 2 + 2 + 3 + 2 + 2 = 42, which is where the familiar 0 to 42 range comes from.

The shortened scales are subsets, not rescalings. Tirschwell and colleagues used stepwise logistic regression on two acute-stroke trial datasets to find the eight items most predictive of a good outcome at three months, and reported them in order of decreasing importance: right leg, left leg, gaze, visual fields, language, level of consciousness, facial palsy, dysarthria. The sNIHSS-8 is all eight and has a maximum of 24; the sNIHSS-5 is the first five and has a maximum of 16. Shortening has a measurable cost. In their validation the C-statistics were 0.80 for the 15-item scale, 0.77 for the sNIHSS-8 and 0.76 for the sNIHSS-5, and the full scale performed significantly better than either shortened version.

Because the three scales are different instruments, the same patient produces three different numbers. The worked example on this page scores 14 on the full scale, 8 on the sNIHSS-8 and 4 on the sNIHSS-5 — not because the patient changed but because fewer items are being counted. That is why the calculator reports the number of items scored and the maximum possible alongside the total, and why a number recorded without its scale cannot be interpreted.

The severity bands need their own warning, which is why the calculator refuses to print one for a shortened scale. The familiar categories — 0 no stroke symptoms, 1 to 4 minor, 5 to 15 moderate, 16 to 20 moderate to severe, 21 to 42 severe — were defined on the 15-item scale, and applying them to a maximum of 24 or 16 would systematically understate severity. Note also that published band schemes disagree: one widely used reference gives mild 1 to 5, mild to moderately severe 5 to 14, severe 15 to 24 and very severe above 25, which puts a score of 5 in two bands at once. This page implements the gapless scheme used to define acute-stroke trial entry criteria and says so rather than choosing silently.

One detail from the sNIHSS deserves stating. Tirschwell's "level of consciousness" is read here as item 1a alone, because the selection was made from the 15-item scale in which 1b and 1c are separate items. If the whole 1a-1b-1c block were intended, the shortened totals could be up to four points higher. That reading is a judgement, and it is written on the page rather than buried in code.

Finally, two things the calculator cannot do. The official form allows an item to be recorded as UN — untestable — where amputation or joint fusion prevents assessing an arm or a leg, and a total that quietly omits an untestable item is not comparable with a complete one. And scoring the NIHSS reliably requires familiarity with the item definitions at certification level: the calculator sums grades, it cannot examine a patient, and it cannot tell whether the grades entered are the ones a trained observer would have assigned.

What is nih stroke scale (nihss) calculator?

The NIH Stroke Scale is a standardised neurological examination that quantifies the deficit caused by an acute stroke. It scores fifteen items covering level of consciousness, gaze, visual fields, facial and limb motor function, ataxia, sensation, language, dysarthria and inattention, and sums them to a total between 0 and 42.

It exists to make stroke severity communicable and comparable — between clinicians, between hospitals, and across the time course of a single patient. It is embedded in acute-stroke pathways, in thrombolysis and thrombectomy trial entry criteria, and in quality registries, and its value there depends on everyone scoring it the same way.

The shortened versions, sNIHSS-8 and sNIHSS-5, were derived by Tirschwell and colleagues in 2002 for the prehospital setting, where a full fifteen-item examination is impractical. They keep the most predictive items and accept a modest loss of discrimination in return for speed.

What none of them is: a diagnosis of stroke, a substitute for imaging, a measure of infarct size, or a prognosis for an individual person. A high NIHSS in a patient with a metabolic encephalopathy or a post-ictal state is a high NIHSS, not a stroke.

How to use this calculator.

1. 01Choose the scale. NIHSS-15 is the full instrument; sNIHSS-8 and sNIHSS-5 are the published shortened scales from Tirschwell 2002 and have maxima of 24 and 16.
2. 02Score every item from your own examination, in the order the official form specifies, and do not go back and change an earlier item on the basis of a later one.
3. 03Grade each item within its own range — the ranges differ: level of consciousness runs 0 to 3, the motor items 0 to 4, and several items only 0 to 2.
4. 04Score the arms and legs separately for each side. They are four items, not two.
5. 05Read the total together with the items scored and the maximum possible, so the number can be interpreted later.
6. 06Do not apply the severity bands to a shortened scale — they were defined on the 15-item version and the calculator will tell you so.
7. 07If an item is untestable because of amputation or joint fusion, the official form records UN and the resulting total is not comparable with a complete one. Note that alongside the score.
8. 08Record which scale produced the number. The same patient scores 14, 8 and 4 on the three scales on this page.

The formula.

The NIH Stroke Scale total is the sum of fifteen ordinal item grades. Their ranges are: 1a level of consciousness 0 to 3; 1b LOC questions 0 to 2; 1c LOC commands 0 to 2; 2 best gaze 0 to 2; 3 visual fields 0 to 3; 4 facial palsy 0 to 3; 5a left arm 0 to 4; 5b right arm 0 to 4; 6a left leg 0 to 4; 6b right leg 0 to 4; 7 limb ataxia 0 to 2; 8 sensory 0 to 2; 9 best language 0 to 3; 10 dysarthria 0 to 2; 11 extinction and inattention 0 to 2. Those maxima sum to 42.

Rounding stage: there is none, and no fractional item grade exists. Every item takes a whole number within its own range and the total is an exact integer sum. This calculator rejects a fractional grade rather than rounding it, because rounding 15.5 either way would move a patient between the moderate and moderate-to-severe bands — a change of clinical category produced by an implementation detail.

The shortened scales are subsets of the same item grades. The sNIHSS-8 sums right leg, left leg, best gaze, visual fields, best language, level of consciousness, facial palsy and dysarthria, for a maximum of 4 + 4 + 2 + 3 + 3 + 3 + 3 + 2 = 24. The sNIHSS-5 sums the first five of those — right leg, left leg, gaze, visual fields and language — for a maximum of 4 + 4 + 2 + 3 + 3 = 16. Because they are subsets, a shortened total can never exceed the full total for the same patient.

The severity bands are applied only to the 15-item total: 0 is no stroke symptoms, 1 to 4 minor stroke, 5 to 15 moderate stroke, 16 to 20 moderate to severe stroke, and 21 to 42 severe stroke. On a shortened scale the calculator returns an explicit statement that bands are not defined, rather than applying 15-item cut-offs to a 24-point or 16-point maximum.

Every item is validated regardless of which scale is selected, so an out-of-range grade on an item the shortened scale ignores is still reported as an error rather than silently discarded. That is deliberate: a typo in an unused field usually means the user is on the wrong scale.

Worked through the example on this page: level of consciousness 1, LOC questions 1, LOC commands 0, gaze 1, visual fields 1, facial palsy 2, left arm 3, right arm 0, left leg 2, right leg 0, ataxia 0, sensory 1, language 0, dysarthria 1, extinction 1. The full total is 1 + 1 + 0 + 1 + 1 + 2 + 3 + 0 + 2 + 0 + 0 + 1 + 0 + 1 + 1 = 14, a moderate stroke. The sNIHSS-8 counts right leg 0, left leg 2, gaze 1, visual fields 1, language 0, level of consciousness 1, facial palsy 2 and dysarthria 1, giving 8 out of 24. The sNIHSS-5 counts the first five of those, giving 4 out of 16.

A worked example.

Frequently asked questions.

References& sources.

1. [1]National Institute of Neurological Disorders and Stroke (NINDS), NIH Stroke Scale. The issuing body for the instrument. (ninds.nih.gov returns HTTP 403 to automated retrieval; item structure verified against the reference below. Consulted 2026-07-29.)
2. [2]National Institutes of Health Stroke Scale — Shirley Ryan AbilityLab Rehabilitation Measures Database. Source of the 15 items with their per-item score ranges (1a 0–3; 1b 0–2; 1c 0–2; 2 0–2; 3 0–3; 4 0–3; 5a/5b 0–4; 6a/6b 0–4; 7 0–2; 8 0–2; 9 0–3; 10 0–2; 11 0–2) and of the 0–42 total. Also the source of the alternative severity scheme this page documents but does not implement. (Full text retrieved 2026-07-29.)
3. [3]Tirschwell DL, Longstreth WT Jr, Becker KJ, et al. Shortening the NIH Stroke Scale for use in the prehospital setting. Stroke. 2002;33(12):2801–2806. Source of the sNIHSS-8 item set in the paper's own order of decreasing importance — right leg, left leg, gaze, visual fields, language, level of consciousness, facial palsy, dysarthria — of the sNIHSS-5 as the first five, and of the validation C-statistics (NIHSS-15 0.80, sNIHSS-8 0.77, sNIHSS-5 0.76). (Abstract retrieved 2026-07-29.)
4. [4]Tirschwell DL, et al. Shortening the NIH Stroke Scale for Use in the Prehospital Setting — publisher copy, Stroke (AHA Journals). Consulted 2026-07-29 as the second retrieval route for the item list and the reported C-statistics.