CHADS2 Stroke Risk Calculator
Use this tool to estimate stroke risk in people with atrial fibrillation using the classic CHADS2 scoring system.
What is the CHADS2 score?
The CHADS2 score is a clinical risk tool used to estimate the annual risk of ischemic stroke in patients with non-valvular atrial fibrillation. It helps clinicians and patients think through anticoagulation decisions by quantifying key risk factors in a simple point system.
CHADS2 stands for:
- Congestive heart failure = 1 point
- Hypertension = 1 point
- Age 75 or older = 1 point
- Diabetes mellitus = 1 point
- Stroke or TIA history = 2 points
How to use this calculator
Step-by-step
Enter age, check each risk factor that applies, and click Calculate Score. The tool returns:
- Total CHADS2 score (0 to 6)
- Estimated annual stroke risk (%)
- General risk category
- A quick summary of contributing factors
Score interpretation (traditional reference ranges)
| CHADS2 Score | Estimated Annual Stroke Risk | General Category |
|---|---|---|
| 0 | 1.9% | Low |
| 1 | 2.8% | Low–Moderate |
| 2 | 4.0% | Moderate |
| 3 | 5.9% | Moderate–High |
| 4 | 8.5% | High |
| 5 | 12.5% | High |
| 6 | 18.2% | Very High |
CHADS2 vs. CHA2DS2-VASc
Modern practice often uses CHA2DS2-VASc because it captures additional risk modifiers (vascular disease, age 65–74, and sex category). Still, CHADS2 remains useful for quick teaching, historical comparisons, and understanding the foundation of AF stroke-risk scoring.
If you are building a workflow for contemporary clinical use, consider including both calculators and linking results to current guidelines.
Practical examples
Example 1: Lower-risk profile
A 62-year-old with atrial fibrillation and no CHF, no hypertension, no diabetes, and no prior stroke/TIA has a CHADS2 score of 0. The estimated annual stroke risk is around 1.9%.
Example 2: Mixed-risk profile
A 77-year-old with hypertension and diabetes has points for age (1), hypertension (1), and diabetes (1), for a total of 3. That corresponds to an estimated annual stroke risk near 5.9%.
Example 3: Prior cerebrovascular event
A patient with prior TIA immediately receives 2 points for that single risk factor. Even with few other comorbidities, this can substantially shift treatment discussions.
Limitations to keep in mind
- It does not directly estimate bleeding risk.
- It is less granular than newer tools such as CHA2DS2-VASc.
- Stroke-risk percentages are population estimates, not guarantees for an individual.
- Clinical context and shared decision-making remain essential.
Bottom line
The CHADS2 calculator is a fast way to frame stroke risk in atrial fibrillation. It is best used as one part of a broader evaluation that includes bleeding risk, patient goals, and current treatment guidelines. Use the score to start informed conversations, not to end them.