The formula used to calculate cable tray capacity is: Cable Tray Capacity = (Tray Width × Tray Depth × Fill Ratio) / Cable Cross-sectional Area Where: Tray Width is the internal width of the cable tray in meters (or millimeters). Calculate cable tray fill ratio, weight loading, and derating factors for multi-standard compliance. This calculator features an interactive interface with advanced visualizations. Save your cable tray sizing calculator results as branded PDF. The International Electrotechnical Commission (IEC) outlines clear guidelines in IEC 61537 for determining the appropriate tray or ladder based on mechanical strength, ventilation, electrical continuity, and fill capacity. IEEE 384 covers cable separation.