CHADS₂ Stroke Risk Calculator
The CHADS₂ score estimates annual stroke risk in atrial fibrillation from five factors (congestive heart failure, hypertension, age ≥75, diabetes and prior stroke/TIA), on a scale of 0 to 6.
Quick answer
CHADS₂ estimates yearly stroke risk in atrial fibrillation by scoring congestive heart failure, hypertension, age 75 or over and diabetes (1 point each) plus prior stroke or TIA (2 points), for a total of 0 to 6. Higher scores mean higher stroke risk; it is the predecessor of CHA₂DS₂-VASc.
CHADS₂ risk factors
Adjusted annual stroke rate ~1.9%.
A CHADS₂ of 0. CHADS₂ is the predecessor of CHA₂DS₂-VASc; most guidelines now use CHA₂DS₂-VASc, which better identifies truly low-risk patients. The anticoagulation decision balances stroke risk against bleeding risk with a clinician.
Validated formula
Congestive heart failure = 1; Hypertension = 1; Age ≥75 = 1; Diabetes = 1; prior Stroke/TIA = 2. Total = 0–6. (CHADS₂ is the predecessor of CHA₂DS₂-VASc.)
Interpretation
- 0— Low risk — adjusted annual stroke rate ~1.9%.
- 1— Adjusted annual stroke rate ~2.8%.
- 2— Adjusted annual stroke rate ~4.0%.
- 3— Adjusted annual stroke rate ~5.9%.
- 4— Adjusted annual stroke rate ~8.5%.
- 5— Adjusted annual stroke rate ~12.5%.
- 6— Highest risk — adjusted annual stroke rate ~18.2%.
How to use the CHADS₂ calculator
- 1Tick the risk factors. Tick congestive heart failure, hypertension, age 75 or over, and diabetes — each worth 1 point.
- 2Add prior stroke or TIA. Tick prior stroke or TIA, which is worth 2 points.
- 3Read the score and risk. The tool totals 0–6 and shows the adjusted annual stroke rate to discuss anticoagulation with a clinician.
Medical disclaimer: This is general health information, not medical advice. It does not diagnose or treat any condition, and the results are estimates based on public reference formulas. Always consult a qualified doctor about your individual health. If you think you may have a medical emergency, contact your local emergency services immediately.
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Book a consultationFrequently asked questions
What is the difference between CHADS₂ and CHA₂DS₂-VASc?⌄
CHA₂DS₂-VASc is the refined, more widely used successor: it adds vascular disease, the 65–74 age band and female sex, and is better at identifying truly low-risk patients. CHADS₂ is the original, simpler version.
What CHADS₂ score is high?⌄
In the original study the adjusted annual stroke rate rises from about 1.9% at 0 points to about 18% at 6 points. A score of 2 or more is generally considered elevated, but most guidelines now use CHA₂DS₂-VASc to make anticoagulation decisions.
Does CHADS₂ decide whether I need anticoagulation?⌄
No. It is one input. The decision weighs stroke risk against bleeding risk and your preferences, and is made with a clinician.
Sources & validation
This calculator reproduces the published CHADS₂ score, validated for annual stroke risk in atrial fibrillation (predecessor of CHA₂DS₂-VASc).
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