CHADS₂ Score Calculator
Estimate stroke risk in atrial fibrillation with the CHADS₂ score — one point each for heart failure, hypertension, age ≥75 and diabetes, two for prior stroke or TIA.
How it works
CHADS₂ = CHF (1) + Hypertension (1) + Age ≥75 (1) + Diabetes (1) + prior Stroke/TIA (2) · score → published annual stroke rate
CHADS₂ was the first widely-used tool to grade stroke risk in non-valvular atrial fibrillation, giving two points to a prior stroke or TIA because it is the strongest predictor. A higher score meant anticoagulation was more clearly beneficial. It has largely been superseded by CHA₂DS₂-VASc, which adds vascular disease, the 65–74 age band and female sex to better identify truly low-risk patients, but CHADS₂ remains a useful, memorable screen.
Worked example
A patient with atrial fibrillation who has hypertension (1) and diabetes (1) but no heart failure, is under 75 and has never had a stroke scores 2, which maps to about a 4.0% annual stroke rate — the high-risk band where anticoagulation is usually considered.
Sources: Gage BF et al., JAMA 2001 — CHADS₂
Frequently asked questions
Should I use CHADS₂ or CHA₂DS₂-VASc?
Most current guidelines prefer CHA₂DS₂-VASc because it is better at confirming who is genuinely low-risk. CHADS₂ is simpler and still informative, but a CHADS₂ of 0 is not the same as truly low risk.
Does a high score mean I must take blood thinners?
It informs the conversation, it does not decide it. Anticoagulation also weighs bleeding risk, patient preference and other factors. That decision belongs to you and your clinician.
Does CHADS₂ apply to any irregular heartbeat?
It was developed for non-valvular atrial fibrillation. It is not validated for valvular AF, other arrhythmias or people without AF.
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Educational clinical estimate only — not a diagnosis, medical advice, or treatment. Scores are screening aids that must be interpreted by a qualified clinician alongside the full clinical picture. Never make care decisions from this tool alone.