CHA₂DS₂-VASc Calculator
Score stroke risk in atrial fibrillation with CHA2DS2-VASc, read the annual risk from an editable table, and compute HAS-BLED alongside it.
CHA₂DS₂-VASc risk factors
HAS-BLED bleeding risk factors
The E component — elderly, over 65 — is taken from the age you entered above and currently scores 1.
CHA₂DS₂-VASc
3 points
Annual stroke risk table (editable data)
Defaults are the untreated annual ischaemic stroke rates published by Friberg, Rosenqvist and Lip from the Swedish Atrial Fibrillation cohort of 182,678 patients (European Heart Journal, 2012) — the same table MDCalc uses. Note that the rate does not rise monotonically at the very top of the scale, because scores of 8 and 9 contain very few patients. Different cohorts report meaningfully different numbers, and background stroke rates have fallen over time, which is exactly why this table is editable rather than baked in.
HAS-BLED bleeding risk
1 points
| HAS-BLED score | Major bleeds per 100 patient-years |
|---|---|
| 0 | 1.13% |
| 1 | 1.02% |
| 2 | 1.88% |
| 3 | 3.74% |
| 4 | 8.70% |
| 5 | 12.50% |
| 6 | too few patients to estimate |
| 7 | too few patients to estimate |
| 8 | too few patients to estimate |
| 9 | too few patients to estimate |
Rates are from the HAS-BLED derivation cohort published by Pisters and colleagues in Chest (2010). The score exists to flag modifiable bleeding risk — blood pressure, labile INR, alcohol, concomitant antiplatelets — not to decide against anticoagulation.
Estimates only, not medical advice. CHA₂DS₂-VASc applies to non-valvular atrial fibrillation and does not apply to moderate-to-severe mitral stenosis or a mechanical heart valve, where anticoagulation is indicated regardless of score. It is a population risk model derived from registry cohorts: it discriminates only modestly at the individual level, the published stroke rates vary substantially between cohorts and have fallen over time, and the female-sex point is a modifier that should not by itself move a woman with no other risk factors into treatment. HAS-BLED shares its risk factors with CHA₂DS₂-VASc, so a high stroke risk usually comes with a high bleeding risk; the correct response is to fix what is modifiable, not to withhold treatment. Anticoagulation is a shared decision with a clinician who knows the whole picture.
What is the CHA₂DS₂-VASc Calculator?
CHA₂DS₂-VASc scores congestive heart failure, hypertension, diabetes, vascular disease and female sex as one point each, age 65 to 74 as one point, and age 75 or over and prior stroke or TIA as two points each, for a maximum of nine.
- Age points derived automatically from an entered age
- Annual stroke risk from a fully editable, clearly sourced lookup table
- HAS-BLED bleeding score on the same page with its published bleed rates
- Point-by-point breakdown of exactly what contributed to the total
- Honest handling of the female-sex point as a risk modifier, not a standalone factor
- Runs entirely offline in the browser — no patient data is transmitted
How to use the CHA₂DS₂-VASc Calculator
- 1
Enter the patient's age — 65 to 74 scores one point and 75 or over scores two, applied automatically.
- 2
Set the sex, then tick the CHA₂DS₂-VASc risk factors that apply.
- 3
Tick the HAS-BLED bleeding risk factors; the elderly component is taken from the age you already entered.
- 4
Read the total score, its risk band and the annual stroke risk drawn from the rate table.
- 5
Edit any rate in the stroke risk table to match the cohort you prefer, or restore the published defaults.
About the CHA₂DS₂-VASc Calculator
The ByteTools CHA₂DS₂-VASc Calculator scores stroke risk in non-valvular atrial fibrillation, derives the age points from an age you type rather than making you decide which band applies, and reports the matching annual stroke risk from a lookup table you can edit. HAS-BLED is computed on the same page, because the two scores are only useful together.
The default stroke rates are the untreated annual figures published from the Swedish Atrial Fibrillation cohort of 182,678 patients, clearly labelled with their source and fully editable — published cohorts differ, background stroke rates have fallen over time, and a table you can update is more honest than one baked into the code.
Everything is computed in your browser and nothing is uploaded. These are estimates for education and cross-checking only, not medical advice: the score is a population risk model that discriminates only modestly at the individual level, and anticoagulation is a shared decision with a clinician who knows the whole picture.
Frequently asked questions
How is the CHA₂DS₂-VASc score calculated?
One point each for congestive heart failure, hypertension, diabetes, vascular disease, age 65 to 74 and female sex, and two points each for age 75 or over and for prior stroke, TIA or thromboembolism. The maximum is nine points.
What CHA₂DS₂-VASc score needs anticoagulation?
Guidelines generally recommend oral anticoagulation at two or more points beyond the sex point, consider it at one, and describe zero as low risk. Because female sex is treated as a risk modifier, a woman whose only point is her sex is managed the same as a man scoring zero.
What is a good HAS-BLED score?
Zero to two is conventionally lower risk and three or more is called high risk. Importantly, a high HAS-BLED score is not a reason to withhold anticoagulation — it is a prompt to correct the modifiable factors such as blood pressure, labile INR, alcohol and concomitant antiplatelets, and to review more often.
Where do the annual stroke risk percentages come from?
The defaults here are the untreated annual ischaemic stroke rates published by Friberg, Rosenqvist and Lip from the Swedish Atrial Fibrillation cohort in the European Heart Journal in 2012. Different cohorts report meaningfully different numbers, so every rate in the table is editable.
Why does the stroke risk not keep rising at scores of 8 and 9?
Because very few patients in the source cohort reach those scores, so the estimates become unstable. The published table genuinely dips at 8 before rising again at 9 — an artefact of small numbers rather than a real reduction in risk.
Does CHA₂DS₂-VASc apply to valvular atrial fibrillation?
No. It was derived and validated in non-valvular AF. Patients with moderate-to-severe mitral stenosis or a mechanical heart valve need anticoagulation regardless of score, and the scoring system should not be used to decide otherwise.
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