Calculate the tray's internal cross-sectional area. Divide the cable area by the tray area and multiply by 100 for a percentage. Consider a 6-inch wide, 4-inch deep cable tray containing 40 cables, each with a diameter of 0. The calculator would help determine if the chosen tray is sufficient or if a larger size is. Properly sizing your cable tray is critical for safety and compliance. Selecting the appropriate cable tray dimensions and size is essential for many kinds of reasons: The size of the cable tray has to be suitable on account. Calculate cable tray fill ratio, weight loading, and derating factors for multi-standard compliance.