NIH Stroke Scale (NIHSS) Calculator

The NIH Stroke Scale (NIHSS) is a 15-item bedside examination that turns an acute stroke assessment into a single reproducible number. It was derived and validated by Brott, Adams and colleagues in Stroke in 1989 and is published as a standardised scale by the National Institute of Neurological Disorders and Stroke (NINDS). The AHA/ASA acute-ischaemic-stroke guideline uses it as the standard instrument for grading severity.

The maths is deliberately plain: the total is the sum of the 15 item scores, with no weights, ratios or transformations. Each item has its own fixed range defined by NINDS:

• Level of consciousness — 1a (0–3), 1b questions (0–2), 1c commands (0–2).
• Best gaze (0–2), visual fields (0–3), facial palsy (0–3).
• Motor arm 5a/5b (0–4 each), motor leg 6a/6b (0–4 each).
• Limb ataxia (0–2), sensory (0–2), best language (0–3).
• Dysarthria (0–2), extinction / inattention (0–2).

Adding the maxima gives a theoretical range of 0 to 42. A total of 0 means no measurable deficit on the scale; higher totals mean larger deficits. Severity is read off the widely published bands used alongside the AHA/ASA guideline:

• 0: No stroke symptoms
• 1–4: Minor stroke
• 5–15: Moderate stroke
• 16–20: Moderate to severe stroke
• 21–42: Severe stroke

The one convention this calculator gets right is the untestable (UN) response. Items 5 (motor arm), 6 (motor leg) and 10 (dysarthria) let you record UN when a limb is amputated or fused, or when speech cannot be tested because the patient is intubated. Following NINDS, an untestable item is documented but scores 0 toward the total — it is never treated as a maximum or a missing value, so it cannot inflate or distort the score.

The scale is scored on the best observed response for each item, reflecting what the patient actually does rather than what they might do. Repeating the whole scale later and comparing totals is how clinicians track whether a stroke is improving or extending. Importantly, the NIHSS quantifies severity only; it does not by itself decide thrombolysis or thrombectomy, which depend on time, imaging and contraindications beyond the scale.

• NINDS — NIH Stroke Scale (official scale, item definitions and point values)
• Brott T, Adams HP Jr, et al. Measurements of acute cerebral infarction: a clinical examination scale. Stroke 1989;20:864–870
• Powers WJ, et al. AHA/ASA Guidelines for the Early Management of Patients With Acute Ischemic Stroke. Stroke 2019;50:e344–e418

The item definitions, point values and severity bands on this page were last cross-checked against these sources on 2026-07-15. This tool is for education and documentation only; it does not provide medical advice and does not replace assessment by a qualified clinician.