Right ventricular (RV) to pulmonary arterial (PA) coupling describes the ability of the RV to augment contractility in response to increased afterload. Several echocardiographic indexes of RV-PA coupling have been defined; however, the optimal numerator in the coupling ratio is unclear. We sought to establish which of these ratios is best for assessing RV-PA coupling based on their relations with 6-minute walk distance (6MWD), N-terminal pro-B-type natriuretic peptide (NT-proBNP), and the Kansas City Cardiomyopathy Questionnaire (KCCQ) in aging adults. In this study of 1,611 Multi-Ethnic Study of Atherosclerosis participants who underwent echocardiography at Exam 6, we evaluated the association between different numerators, including tricuspid annular planar systolic excursion (TAPSE), fractional area change (FAC), RV free wall strain, and tissue Doppler imaging S' velocity to pulmonary artery systolic pressure (PASP) with 6MWD, NT-proBNP, and KCCQ score, adjusted for socioeconomic and cardiovascular disease risk factors. Our cohort had a mean age of 73 ± 8 years, 54% female, 17% Chinese American, 22% African American, 22% Hispanic, and 39% White participants. The mean ( ± SD) TAPSE/PASP, FAC/PASP, tissue Doppler imaging S' velocity/PASP, and RV free wall strain:PASP ratios were 0.7 ± 0.2, 1.3 ± 0.3, 0.5 ± 0.1, and 0.8 ± 0.2, respectively. All RV-PA coupling indices decreased with age (p <0.0001 for all). TAPSE:PASP ratio was lower in older (³85 years) female (0.59 ± 0.14) versus male (0.65 ± 0.17) participants (p = 0.01), whereas FAC/PASP ratio was higher in the same female versus male participants (p <0.01). TAPSE/PASP and FAC/PASP ratios were significantly and strongly associated with all NT-proBNP, 6MWD, and KCCQ scores in fully adjusted and receiver operating characteristic analysis. In older community-dwelling adults free of heart failure and pulmonary hypertension, both FAC/PASP and TAPSE:PASP ratios are optimal for assessment of RV-PA coupling based on its association with 6MWD, NT-proBNP, and KCCQ score. FAC/PASP ratio has the additional benefit of reflecting age and gender-related geometric and functional changes.