Background <p>The left-to-right symmetry of lower limbs based upon radiographs is confirmed. The Coronal Plane Alignment of the Knee (CPAK) Classification proposes nine coronal plane phenotypes based on the arithmetic hip-knee-ankle angle (aHKA) and joint line obliquity (JLO). This study investigates the bilateral consistency of the CPAK classification in healthy individuals.</p> Methods <p>Long-leg standing radiographs of 270 participants (135 women and 135 men) were analyzed for alignment parameters, including the mechanical hip-knee-ankle angle (mHKA), lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), and joint line convergence angle (JLCA). Based on the aHKA and JLO, the CPAK type of knee was documented, and the bilateral consistency was evaluated. The distribution of CPAK and angle measurements were compared between bilateral lower limbs. Inter- and within-subject variability was assessed, with correlation coefficients (<i>r</i>) calculated to estimate bilateral symmetry.</p> Results <p>The overall bilateral consistency of CPAK was observed in 62.2% (168 of 270) of participants, with consistency rates of 60% (81 of 135) in women and 64.4% (87 of 135) in men. Type Ⅱ was the most common type in lower Limbs with bilateral consistency, accounting for 42.9% (72 of 168). There was no significant difference in the distribution of CPAK between bilateral limbs (<i>p</i> = 0.547). No significant side differences were found in the mHKA, MPTA, LDFA, and JLCA measurements. Correlation analyses indicated bilateral alignment correlations ranging from <i>r</i> = 0.695 for mHKA to <i>r</i> = 0.815 for MPTA (<i>p</i> &lt; 0.001).</p> Conclusions <p>Bilateral consistency was relatively low in healthy individuals when the CPAK classification was applied. Low consistency restricts the utility of the contralateral CPAK as a reliable reference for planning coronal alignment in total knee arthroplasty.</p>