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Free Wells’ Criteria for PE Calculator (2026)
Wells’ Criteria for Pulmonary Embolism is a seven-item clinical prediction rule that estimates the pretest probability of PE in a patient with clinically suspected pulmonary embolism, so that probability can be paired with a D-dimer test or direct imaging in a structured diagnostic pathway. It weights clinical signs of deep vein thrombosis, whether PE is the most likely diagnosis, heart rate, recent immobilization or surgery, prior venous thromboembolism, hemoptysis, and active malignancy, for a total score from 0 to 12.5. The calculator below reports both the original three-tier risk band (low, moderate, high, each with an associated PE prevalence) and the simpler two-tier “dichotomized” version widely used in modern emergency-department pathways (PE unlikely vs. PE likely) — because the two do not always agree at the margin, and clinicians should know which version their department’s protocol expects. It is built for emergency physicians, hospitalists, and pulmonology or vascular medicine clinicians working up suspected PE. Check the criteria that apply below to calculate a patient’s score instantly.
Clinical decision-support aid, not a substitute for clinical judgment. These tools implement published scoring criteria for education and workflow support. They are not a medical device and have not been reviewed by the FDA or any regulatory body. Every result should be interpreted by a qualified clinician in the context of the full clinical picture, not used as a standalone diagnostic or treatment decision.
Pulmonary embolism pretest probability
Wells’ Criteria
Check every criterion that applies. The readout reports the traditional 3-tier score, the simplified 2-tier dichotomized rule most EDs use to route patients to D-dimer versus imaging, and a component breakdown.
Wells PS, Anderson DR, Rodger M, et al. Thromb Haemost. 2000;83(3):416–420 · Christopher Study Investigators. JAMA. 2006;295(2):172–179.
A fully worked example
Consider a patient with a heart rate of 108 beats per minute (+1.5), a previous objectively-diagnosed DVT (+1.5), and recent surgery followed by 4 days of immobilization (+1.5). There are no clinical signs of DVT, PE is not judged more likely than an alternative diagnosis, there is no hemoptysis, and no active malignancy. Adding the three positive criteria gives a total of 4.5 out of 12.5. On the traditional three-tier scale, 4.5 falls in the moderate-risk band, corresponding to roughly 16.2% PE prevalence in the original validation cohort. But on the simplified dichotomized rule — where a score of 4 or below is “PE unlikely” (proceed to D-dimer) and above 4 is “PE likely” (proceed directly to imaging) — this same 4.5 crosses into the “PE likely” category, meaning CT pulmonary angiography rather than a D-dimer is the recommended next step. This is a genuinely useful teaching point: the two versions of the same underlying score can disagree right at a boundary case like this one, so it matters which version a department’s protocol specifies. These same three criteria are already loaded as the calculator’s defaults above.
Methods, assumptions, and when not to use Wells’ Criteria
For a manuscript methods section, Wells’ Criteria can be cited in a single sentence: “Pretest probability of pulmonary embolism was estimated using the Wells’ Criteria, reported as both a three-tier risk score and a dichotomized ‘PE likely/unlikely’ classification (Wells et al., Thromb Haemost 2000; Christopher Study Investigators, JAMA 2006).” Because Wells’ Criteria is a fixed, published point-score rather than a fitted or site-specific model, citing its derivation study and the dichotomized-version validation study is sufficient methodological documentation.
Wells’ Criteria is designed to be paired with a D-dimer test or imaging as part of a structured diagnostic pathway — it is a pretest-probability tool, not a standalone rule-out or rule-in test, and a low score does not eliminate the need for further work-up when clinical suspicion remains high. It is also less well validated in pregnancy, where physiologic changes such as elevated heart rate and baseline D-dimer elevation reduce its discriminative performance and pregnancy-specific pathways are generally preferred, and in patients already therapeutically anticoagulated, in whom the pretest probability of a new clot is altered by treatment already in place. Clinical gestalt that strongly disagrees with the calculated score should prompt reconsideration, not automatic deference to the number.
What are the seven criteria in Wells’ Criteria for PE?
The seven weighted criteria are: clinical signs and symptoms of deep vein thrombosis, such as leg swelling and pain on palpation of the deep veins (3 points); pulmonary embolism being the single most likely diagnosis, or equally likely compared to alternatives (3 points); heart rate above 100 beats per minute (1.5 points); immobilization for at least 3 days or surgery within the previous 4 weeks (1.5 points); a previous, objectively diagnosed PE or DVT (1.5 points); hemoptysis (1 point); and malignancy treated within the last 6 months, or being treated palliatively (1 point). The maximum possible score is 12.5.
What’s the difference between the 3-tier and dichotomized versions?
The original 2000 derivation used three risk tiers: low (under 2 points, roughly 1.3% PE prevalence), moderate (2 to 6 points, roughly 16.2% prevalence), and high (above 6 points, roughly 40.6% prevalence). The 2006 Christopher Study validated a simpler two-tier “dichotomized” approach that many emergency departments now use operationally: a score of 4 or below is called “PE unlikely,” supporting a D-dimer-first strategy, while a score above 4 is called “PE likely,” supporting proceeding directly to CT pulmonary angiography. Because the cut points do not line up exactly with the three-tier bands, a score can be “moderate” on one scale and “likely” on the other — exactly what happens in the worked example above.
When should D-dimer testing be skipped in favor of imaging?
Under the dichotomized approach, a “PE likely” result (score above 4) is generally an indication to proceed directly to CT pulmonary angiography rather than obtain a D-dimer first, because a positive D-dimer would not meaningfully change management in a patient already assessed as high pretest probability, and a negative D-dimer is less reliably reassuring at higher pretest probabilities. D-dimer testing is most useful for excluding PE in patients who fall in the “PE unlikely” range, where a normal result can reasonably avoid imaging altogether.
Primary references
Wells PS, Anderson DR, Rodger M, et al. Derivation of a simple clinical model to categorize patients probability of pulmonary embolism: increasing the model’s utility with the SimpliRED D-dimer. Thromb Haemost. 2000;83(3):416–420.
Christopher Study Investigators. Effectiveness of managing suspected pulmonary embolism using an algorithm combining clinical probability, D-dimer testing, and computed tomography. JAMA. 2006;295(2):172–179.
Studying ED pulmonary-embolism workup patterns?
Diagnostic-pathway questions like D-dimer-first versus imaging-first are exactly the kind of registry cohort research that needs careful case definition. Editverse’s NTDB/TQP Trauma Registry Study service handles registry access, cohort definition, risk-adjusted modelling, and a publication-ready manuscript for ED and PE-workup research. See the registry study service