Functional capacity in heart failure. Free to use.
NYHA Functional Class (New York Heart Association Functional Classification) is a validated clinical instrument used to assess functional capacity in heart failure. The instrument contains 1 item.
Source / attribution: Criteria Committee NYHA, 9th ed., 1994
The instrument's primary construct — functional capacity in heart failure — is operationalized through a fixed set of items, each with a defined response format. This standardisation is what allows NYHA Functional Class scores to be compared meaningfully across clinicians, sites, and studies.
Like all screening or assessment instruments, NYHA Functional Class is a structured aid — not a diagnostic test in isolation. Results should be interpreted alongside history, examination, and clinical context. Where a score crosses an actionable threshold, the next step is typically a more detailed clinical evaluation rather than a definitive diagnosis.
Answer all 1 item below to see your NYHA Functional Class score and interpretation.
Each item is scored on a 4-point scale (1–4). Your score updates live as you answer.
All scoring runs in your browser. No data is sent anywhere — close the tab and the answers are gone.
NYHA Functional Class uses simple summation: each item's selected response is converted to a numeric value, and the values are added to produce a total score. Reverse-scored items are inverted before summation.
Scoring notes: Educational use only.
The cutoffs below are drawn from the published validation literature. Always interpret in clinical context.
| Score range | Band | Interpretation |
|---|---|---|
| 1–1 | Class I | No functional limitation. |
| 2–2 | Class II | Slight limitation. |
| 3–3 | Class III | Marked limitation. |
| 4–4 | Class IV | Severe — symptoms at rest. |
This is an illustrative walkthrough, not a real patient. Follow the same four steps with your own answers — or use the live calculator at the top of this page.
Read each question and choose the response that best fits. Each response has a number next to it — that number is the item's score. The example below uses illustrative answers.
| # | Item | Example response | Score |
|---|---|---|---|
| 1 | Functional class | III — Marked limitation; less than ordinary activity causes symptoms | 3 |
Add up all the item scores you noted in Step 1.
3 = 3
Find the row in the interpretation table whose range contains your total:
Total = 3 falls between 3 and 3 → Class III
Class III. Marked limitation.
A score is one input alongside history and examination. NYHA Functional Class supports clinical judgment — it does not replace it.
If NYHA Functional Class doesn't fit your context, related instruments in cardiology include:
| Scale | Measures | Items | Time |
|---|---|---|---|
| CHA2DS2-VASc | Annual stroke risk in non-valvular atrial fibrillation | 8 | — |
| HAS-BLED | 1-year risk of major bleeding on oral anticoagulation | 9 | — |
| HEART Score | 6-week MACE risk in ED patients with chest pain | 5 | — |
| APGAR Score | Rapid assessment of newborn at 1 and 5 min | 5 | — |
| ASA Physical Status | Pre-operative health status | 1 | — |
| CURB-65 | 30-day mortality in community-acquired pneumonia | 5 | — |
| Glasgow Coma Scale | Level of consciousness after head injury | 3 | — |
| Katz ADL | Functional independence in basic ADLs | 6 | — |
NYHA Functional Class (New York Heart Association Functional Classification) is a validated instrument that assesses functional capacity in heart failure. It is designed for clinicians, medical students, evidence-synthesis researchers. The 1 items are summed to produce a total score.
NYHA Functional Class contains 1 items. Item scores are summed to produce the total. Scores run from 1 to 4, grouped into 4 interpretation bands from ‘Class I’ up to ‘Class IV’.
On the NYHA Functional Class (total score 1–4), scores of 4 fall in the ‘Class IV’ band — interpreted as: Severe — symptoms at rest. The full ladder is: 1 — Class I: No functional limitation.; 2 — Class II: Slight limitation.; 3 — Class III: Marked limitation.; 4 — Class IV: Severe — symptoms at rest. A higher score reflects a more severe presentation, and crossing a cutoff is a prompt to step up assessment or care — but these bands are screening thresholds, not diagnoses.
Scores of 1 fall in the ‘Class I’ band: No functional limitation. A low score is reassuring but does not by itself rule out the underlying condition — if symptoms or clinical suspicion persist, reassess over time or use a complementary evaluation rather than relying on the number alone.
Yes — NYHA Functional Class is in the public domain and free for clinical, educational, and research use without permission. You can use this calculator and the scale itself freely; if you publish results or reproduce the scale, cite the original source paper.
Criteria Committee, NYHA. 9th ed. Boston: Little Brown; 1994. This is the original publication for the NYHA Functional Class — the reference to cite when reporting results.
No. NYHA Functional Class is a structured assessment aid, not a diagnostic test. Its proper role is clinical assessment of functional capacity in heart failure — it standardizes assessment and flags who needs closer evaluation, but the result must be weighed alongside history, examination, and clinical context. When a score conflicts with your clinical impression, clinical judgment takes precedence; treatment decisions should never rest on a screening score alone.
NYHA Functional Class is supported by the following peer-reviewed sources: