This study evaluates a new equation for defining maximum desk height in educational settings, comparing it with the traditional Chaffin and Anderson-based equation through biomechanical analysis. The new equation, based on 30° shoulder abduction and 35° flexion, was tested against established criteria in a quasi-experimental study involving 34 participants. Using motion capture and surface EMG, we analyzed shoulder kinematics and muscle activity during six standardized tasks performed at two desk heights. Results showed no significant differences in shoulder kinematics safety parameters between setups, while EMG data revealed consistent muscle activity patterns below 10 % MVC for both conditions. Performance metrics across tasks showed no significant differences between desk heights. Preference analysis indicated no overall significant difference between conditions, although gender-specific patterns emerged with 66 % of women preferring the proposed height. Discomfort levels were comparable between conditions. Theoretical testing of the new equation on existing databases (n: 2261 students; n: 2946 workers) demonstrated improved anthropometric fit, increasing match rates from 63 % to 94 % in students and reducing high mismatch cases from 46.7 % to 7.1 % in workers. The findings validate that the new equation maintains biomechanical safety while significantly improving anthropometric fit. This alignment between biomechanical and anthropometric criteria represents an advancement in educational furniture design, particularly relevant for contemporary educational tasks requiring forearm support.