Conduit Fill Calculator
Calculate raceway fill for power, low-voltage, communications, and security cables and identify the minimum listed conduit size that meets the selected fill limit.
Raceway and Conductors
Select the conduit, then add power conductors, low-voltage wire, communications cable, or custom cable diameters.
Calculated Results
The allowable percentage changes automatically with conductor count.
Calculated fill—
Maximum allowed—
Used conductor area—
Allowable fill area—
Total conductors—
Remaining allowable area—
Status: Add conductors to calculate.
A minimum conduit-size recommendation will appear here.
| Conductor | Qty. | Area each | Total area |
|---|---|---|---|
| No calculation yet. | |||
This tool uses 53% for one cable or conductor, 31% for two, and 40% for three or more. Cat5e, Cat6, coaxial, and security-cable values are based on representative outside diameters and can vary materially by manufacturer, shielding, listing, and jacket construction. Use the Custom Cable OD option for manufacturer-specific dimensions. Verify the adopted NEC edition, cable listing, raceway dimensions, cable-bending limits, pulling requirements, derating, firestopping, separation rules, and local authority requirements before construction.
