Gait analysis is a fundamental tool for understanding joint function and identifying asymmetries in joint moments, which can signal underlying pathologies or potential risk factors for joint damage. Despite the widespread use of symmetry analysis in assessing gait across various conditions, including osteoarthritis and post-injury recovery, there remains no clear objective evidence on joint moment symmetry in healthy adults to serve as a comparison for pathological populations. This study aimed to define the range of joint moment asymmetry during walking in healthy adults. Twenty-one asymptomatic individuals aged 40 years and older underwent three-dimensional gait analysis at a self-selected walking speed. The total knee joint moment was calculated as a composite measure of the net external knee frontal, sagittal, and transverse moments, and absolute inter-limb asymmetry in the total knee joint moment was calculated for all participants. Paired samples t-tests were used to assess for differences in total knee joint, frontal, sagittal, and transverse moments between knees. No significant differences in any knee joint moment outcomes were found between knees. Findings indicated that the upper limit of absolute total joint moment asymmetry in asymptomatic individuals was 14 %. The establishment of this threshold provides a critical reference for clinicians and researchers to identify asymmetries that may deviate from healthy adult ranges.