Calculate required cable tray width per NEC Article 392 using the 50% fill ratio rule. Enter cable ODs and quantities to get minimum tray cross-section area and recommended standard tray width (6", 12", 18", 24", 30", 36") for multi-conductor power and control cable installations. Open the full calculator for the best experience. Save your cable tray sizing calculator results as branded PDF. Properly sizing your cable tray is critical for safety and compliance. Follow these simple steps: Define Tray Dimensions: Enter the width and depth of your planned cable tray (in mm or inches).