Cable Tray Fill Calc

30 cables in a 12-inch ladder tray - over the 50% NEC 392 fill? 4 tray types, AWG #14 to 4/0, or metric mm². $4.99 one-time, no login.

Built for electricians, cable-tray installers, and EEs who need a quick NEC 392 fill check on the deck - not a dashboard you log into.

WHAT IT DOES Computes total cable cross-section as a percentage of tray area and compares against the NEC 392 maximum fill: 50% for ladder and wire-basket trays, 40% for solid-bottom and channel trays. Flags over-fill and shows how many more cables of the same type fit before the limit.

INPUTS

• Unit system: SAE (inches) or Metric (mm)
• Tray type: Ladder, Solid Bottom, Wire Basket, Channel
• Tray size: 9 imperial sizes / 9 metric sizes
• Cable type: AWG #14 to 4/0 (SAE) or 1.5 to 50 mm² (Metric)
• Cable count

RETURNS

• Tray area (sq in or sq mm)
• Total cable area (sq in or sq mm)
• Fill percentage
• Maximum allowed fill per NEC 392 (50% or 40% depending on tray type)
• Remaining capacity in number of cables
• Over-fill warning (red banner) when above the allowed percentage

WHY THIS APP, NOT THE FREE ONES

• Math is shown - tray area, total cable area, and the percentage all visible.
• NEC 392 fill limits applied automatically - pick the tray type and the cap follows.
• Works offline - basements, riser shafts, mid-deck rough-ins. Always available.
• No login. No ads. No telemetry. No subscription.

PRICING $4.99. Pay once, own it. Lifetime access on iPhone, iPad, and Mac via Family Sharing.

NOT A SUBSTITUTE FOR AHJ-stamped electrical drawings. Manufacturer cable-tray load tables. NEC 392 ampacity derating for closely-spaced multiconductor cables - this app handles cross-section fill only, not the temperature derate. Always cross-reference the engineer-stamped layout.