Calculate cable tray fill percentage using the area-fill method — ladder/ventilated trough (50% limit) or solid-bottom tray (40% limit) per NEC Article 392. Instant pass/fail against code limits.
// INPUTS
// Results update automatically as you type
// TRAY
inches (NEC)
inches (NEC)
// CABLES
inches (NEC)
Tray Internal Area—in²
Total Cable Area—in²
Fill Percentage—%
Permitted Fill Limit—%
Status—
Disclaimer: This tool applies the general area-fill method (50%/40% by cross-sectional area) as a practical design check. NEC Article 392 defines additional sum-of-diameter criteria for cables ≤4/0 AWG at specific tray widths — verify against NEC Table 392.22(A) directly for code-compliance sign-off. Ampacity derating is a separate check — see the Cable Ampacity Calculator.
// EXCEEDS LIMIT — RECOMMENDATIONS
Please check inputs — all values must be positive.
// RELATED TOOL
Cable Ampacity Calculator
Fill compliance and ampacity derating are separate checks. Once your tray fill is confirmed, use the Cable Ampacity Calculator to verify each cable's derated ampacity for grouped installation still meets the design load.