Maximal oxygen uptake (VO2max) indicates cardiovascular endurance in evaluating overall health and physical performance. The CPX method is accurate, but accessibility is lower due to issues related to cost and complexity. For this reason, the Harvard Step Test and Queen's College Step Test are drawing interest. Step-based tests are influenced by factors such as leg length, requiring an investigation into the correlation between leg length and VO₂max estimation using these methods. This study investigates the influence of leg length on predicted VO₂max (pVO2max) determined through both the Harvard Step Test and the Queen's College Step Test. The assessment of VO2max was carried out using CPX on a treadmill. Measurements were obtained through the Harvard Step Test and Queen's College Step Test on steps. The participants were informed about the experimental procedure, and the experiment was conducted 24 hours later. The experiment maintained controlled conditions, and each measurement was conducted as a single trial, repeated three times for accuracy. The study found a significant positive correlation (r = 0.595, P < 0.05) between CPX VO2max and lower leg length. Lower leg length was found to significantly influence exercise intensity as determined by both the Harvard Step Test pVO2max (explaining 35.4% of the variance, P < 0.05) and the Queen's College Step Test pVO2max (explaining 30% of the variance, P < 0.05). It is recommended to adjust the step height to the individual's body size when estimating exercise difficulty or pVO2max using step-based exercises.