Background Hypertension (high blood pressure) is a modifiable risk factor for cardiovascular disease. However, patients may lack confidence in their understanding of what constitutes normal/healthy blood pressure, potentially affecting intentions to seek necessary care. The American Heart Association defines normal/healthy blood pressure as <120/80 mm Hg, with a 130/80 mm Hg threshold for hypertension diagnosis. Methods Our US sample ( N = 6,592) included 1,342 adults with hypertension alone and 795 with hypertension and relevant comorbidities (heart disease, kidney disease, and diabetes mellitus). We assessed confidence in understanding blood pressure numbers, knowledge of thresholds for normal/healthy blood pressure (“normal or healthy blood pressure is below . . .”; counting 120–130/80 mm Hg as correct), and intentions to seek care for randomly assigned blood pressure readings of 142/91 (stage 2 hypertension), 132/69 (stage 1 hypertension), or 118/78 mm Hg (normal/healthy blood pressure). Results Among nonhypertensive participants, 55% expressed confidence in their understanding of blood pressure numbers, but only 36% knew the upper thresholds for normal/healthy blood pressure. Among participants with hypertension alone, 78% were confident while 47% were knowledgeable. Among participants with hypertension and comorbidities, 81% were confident and 40% were knowledgeable. Participants who were confident (v. not) were more likely to express intentions to act on stage 2 hypertension readings but less likely to express intentions to act on stage 1 readings, even after adjustment for knowledge, hypertension diagnosis, and sociodemographics. Limitations Confidence, knowledge, and intentions were each measured with 1 question. Conclusions Independent of knowledge, confidence was associated with greater willingness to act on stage 2 hypertension readings but reduced willingness to act on stage 1 hypertension readings. Interventions aiming to improve hypertension care-seeking behavior should improve confidence in accurate knowledge. Highlights Hypertension or high blood pressure is a major risk factor for heart disease. Most Americans do not know that normal/healthy blood pressure levels are ≤120/80 mm Hg, yet they are confident that they know this information. Inappropriate confidence in understanding of blood pressure numbers undermines intentions to seek care for stage 1 hypertension blood pressure readings.