CHADS2 Score Calculator

CHADS2 score for stroke risk in non-valvular atrial fibrillation (0–6).

For educational and clinical reference. Not a substitute for medical judgment. See the medical disclaimer.
Score
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Interpretation
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References

  1. Gage BF, Waterman AD, Shannon W, et al. Validation of clinical classification schemes for predicting stroke. JAMA. 2001;285(22):2864-2870.

What is CHADS2 Score?

The CHADS2 score is a clinical prediction rule for estimating annual stroke risk in patients with non-valvular atrial fibrillation. Developed by Gage et al. in 2001, it assigns one point each for congestive heart failure, hypertension, age ≥75, and diabetes, and two points for prior stroke or transient ischemic attack — yielding a total of 0 to 6. A score of 0 indicates low risk (~1.9% per year), while ≥2 traditionally warranted oral anticoagulation. CHADS2 has largely been superseded by CHA2DS2-VASc, which more reliably identifies patients at truly low risk who do not benefit from anticoagulation.

How to use

  1. Check each risk factor that applies.
  2. The CHADS2 score (0–6) and annual stroke risk update instantly.
  3. For modern AF management, CHA2DS2-VASc is preferred.

Frequently asked questions

Should I use CHADS2 or CHA2DS2-VASc?

CHA2DS2-VASc is preferred in current guidelines (AHA/ACC/ESC) because CHADS2 may under-estimate stroke risk in patients scored "low".

What CHADS2 score warrants anticoagulation?

Most guidelines recommend anticoagulation when CHADS2 ≥ 2; CHADS2 = 1 is borderline (consider).

Does CHADS2 apply to valvular AF?

No. Valvular AF (mechanical valves, moderate-to-severe mitral stenosis) requires anticoagulation regardless of CHADS2.

Is the stroke rate the same with anticoagulation?

No — CHADS2 estimates baseline (untreated) annual stroke risk. Warfarin reduces stroke by ~ 64%; DOACs slightly more.

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