This study compared disability levels between community-dwelling adults in the United States and South Korea using two national surveys of the United States and Korean National Health and Examination Survey (NHANES and KNHANES). The Rasch common-item equating method was used to create the same measurement framework and compared average disability levels. The disability levels between the two countries were estimated using the current disability estimation method (percentage of people having disability based on a single question). A higher percentage of American adults (20.5%) showed disability than the Korean adults (9.6%) based on the current estimation method; however, using the Rasch model American adults had significantly less disability (Mean = -3.00 logits, SD = 1.67) than the Korean adults (Mean = -2.48 logits, SD = 2.13). Complementary to comparisons of the frequency of disability, comparison of the combined magnitude and strength of disability across countries provides new information that may better inform public health and policy decisions.