CHA2DS2-VASc Stroke Risk Calculator
Use this tool to estimate stroke risk in people with atrial fibrillation (AF) based on the CHA2DS2-VASc score.
Score:
Estimated annual stroke risk:
General guidance:
Educational use only. This calculator does not replace clinical judgment. Anticoagulation decisions should be made with a licensed clinician, considering bleeding risk, patient preferences, and current guidelines.
What is the CHADS VASc 2 calculator?
The “CHADS VASc 2 calculator” usually refers to the CHA2DS2-VASc score. It is a widely used clinical scoring system to estimate the risk of ischemic stroke in people with non-valvular atrial fibrillation (AF). AF can allow blood clots to form in the heart, and those clots can travel to the brain and cause stroke.
The score helps clinicians and patients decide whether blood thinners (oral anticoagulants) are likely to provide net benefit. Higher scores generally mean higher stroke risk and a stronger rationale for anticoagulation.
How the score is built
CHA2DS2-VASc components
- C — Congestive heart failure / LV dysfunction: +1
- H — Hypertension: +1
- A2 — Age 75 years or older: +2
- D — Diabetes mellitus: +1
- S2 — Prior stroke/TIA/systemic embolism: +2
- V — Vascular disease (prior MI, PAD, or aortic plaque): +1
- A — Age 65–74 years: +1
- Sc — Sex category (female): +1
Maximum total score is 9. Age contributes either +2 or +1 (not both).
Estimated annual stroke risk by score
Different cohorts report slightly different percentages. The table below provides commonly cited approximate values used for quick education and triage:
| CHA2DS2-VASc Score | Approx. Stroke Risk / Year |
|---|---|
| 0 | ~0.2% |
| 1 | ~0.6% |
| 2 | ~2.2% |
| 3 | ~3.2% |
| 4 | ~4.8% |
| 5 | ~7.2% |
| 6 | ~9.7% |
| 7 | ~11.2% |
| 8 | ~10.8% |
| 9 | ~12.2% |
How to interpret results in practice
General clinical direction
- Low risk: usually no anticoagulation recommended.
- Intermediate risk: anticoagulation may be considered after shared decision-making.
- Higher risk: anticoagulation is generally recommended unless contraindicated.
A key nuance: many guideline frameworks effectively focus on non-sex risk factors. Female sex can modify risk, but by itself may not trigger treatment in younger otherwise low-risk patients.
Important limitations
- The score was designed for AF stroke risk, not for people without AF.
- It should not be used alone to make treatment decisions.
- Bleeding risk matters too (for example, HAS-BLED is often reviewed alongside this score).
- Kidney function, frailty, falls risk, medication interactions, and patient values are also important.
- Guidelines evolve; local and national recommendations can differ.
How to use this calculator correctly
- Enter age and select sex category.
- Check each condition that applies.
- Click Calculate Score.
- Review total points, estimated annual stroke risk, and general guidance.
- Discuss final decisions with a clinician.
FAQ
Is this the same as CHADS2?
Not exactly. CHADS2 is an older score. CHA2DS2-VASc adds additional risk factors and refines age weighting, so it is more commonly used today for AF stroke risk stratification.
Does a higher score always mean immediate anticoagulation?
Usually it strengthens the case, but treatment still depends on overall clinical context and contraindications. Shared decision-making remains essential.
Can this replace a doctor visit?
No. This page is a learning and estimation tool only. Use it to prepare for discussion with your healthcare team, not as a final diagnosis or prescription guide.