Detecting and classifying factors that contribute to age-related balance decline are essential for targeted interventions. Dynamic postural tests that challenge neuromuscular balance control are important to detect subtle deficits that affect functional balance in healthy aging. How does healthy aging affect specific components of dynamic postural control as measured by the simplified Star Excursion Balance Test (SEBT)? Twenty healthy younger (18–39 years) and twenty healthy older (58–74 years) adults performed the standardized simplified SEBT, which involved standing on one leg and reaching the contralateral leg as far as possible in the anterior, posteromedial, and posterolateral directions. Optical motion capture was used to quantify the maximum reach distance normalized by body height (%H) for three repeated trials in each direction per leg. Linear mixed effects models and pairwise comparisons of estimated marginal means were used to assess differences (p < 0.05) in normalized maximum reach distance by age group, reach direction, and leg dominance. Intersubject and intrasubject variability were also assessed by age group using coefficients of variation (CV). Healthy older adults had less dynamic postural control compared to younger adults, with shorter reach distances in the anterior (7.9 %), posteromedial (15.8 %), and posterolateral (30.0 %) directions (p < 0.05). Leg dominance and sex did not significantly affect SEBT score for either age group (p > 0.05). Low intrasubject variability (CV<0.25 %) was found for repeated trials in both the older and younger participants. Therefore, the comparatively higher intersubject variability (Range CV=8–25 %) was mostly attributed to differences in SEBT performance across participants. Quantifying dynamic postural control in healthy older adults in a clinical setting is important for early detection of balance decline and guiding targeted and effective treatment. These results support that the simplified SEBT is more challenging for healthy older adults, who may benefit from dynamic postural training to mitigate age-related decline. •The SEBT reliably detects balance decline with healthy aging (60+ years).•Posterior unilateral leg movements were most challenging for older adults.•SEBT learning capacity and leg symmetry were similar across age groups.