This is an app to calculate the 4-PEPS 4-Level clinical pretest probability for pulmonary embolism as described in: https://jamanetwork.com/journals/jamacardiology/fullarticle/2776853. The creator of this app has no affiliation with the study group, but found it convenient to have an easy way to calculate the score on a mobile device, as well as being a reminder of the items that should be taken into consideration when evaluating a patient with suspected pulmonary embolism.