CHADS₂ Score Calculator
CHADS₂ summarizes stroke risk factors in nonrheumatic atrial fibrillation. Historical adjusted event rates below apply to the original 2001 cohort (ages 65–95; no warfarin at discharge); they are not patient-specific risk predictions or a rule for anticoagulation decisions.
Complete the fields, then select Calculate.
5 fields are required.
CHADS₂ total score
Answer all five questions and select Calculate.
Rates are NRAF model-adjusted ischemic strokes per 100 patient-years in the original cohort, not modern treated-patient estimates or personal absolute probabilities.
Was this calculator easy to use?
Your response is saved to improve this site. Calculator inputs and results are not sent.
Thank you! You can recommend this calculator with the share button above.
Scoring method, original event rates, and limits
Points
One point each for recent congestive heart failure, hypertension, age ≥75 years, and diabetes; two points for previous stroke or TIA. The score ranges from 0 to 6. Missing answers must not be counted as No.
Worked example (hypothetical)
Heart failure, hypertension, and previous stroke/TIA, but age below 75 and no diabetes: 1+1+2=4 points; the original adjusted rate was 8.5 events/100 patient-years (95% CI 6.3–11.1).
Historical incidence table
| Score | Events / 100 patient-years | 95% CI |
|---|---|---|
| 0 | 1.9 | 1.2–3.0 |
| 1 | 2.8 | 2.0–3.8 |
| 2 | 4.0 | 3.1–5.1 |
| 3 | 5.9 | 4.6–7.3 |
| 4 | 8.5 | 6.3–11.1 |
| 5 | 12.5 | 8.2–17.5 |
| 6 | 18.2 | 10.5–27.4 |
Population and limitations
The original cohort comprised 1,733 nonrheumatic atrial fibrillation patients aged 65–95 and not prescribed warfarin at discharge. The adjusted rate assumed no aspirin. Do not interpret this as an annual rate for people receiving contemporary anticoagulants or younger patients, and do not infer an anticoagulant prescription or dose.
Sources and review
Original CHADS₂ model (Gage et al., 2001); sources verified 2026-11-10. Numeric verification: implementer-verified.