Estimate conduit size from wire gauge, conductor quantity, conduit type, and conduit fill limit. This calculator helps estimate conduit fill area, fill percentage, spare capacity, and recommended conduit trade size.
Wire area:
The calculator estimates conductor outside area from a simplified wire area table.
Total fill:
Primary wire area and ground wire area are added together to estimate total wire area inside the conduit.
Conduit selection:
The calculator checks common conduit trade sizes and selects the first size that stays within the chosen fill limit.
A conduit size calculator helps estimate conduit trade size before planning an electrical run.
It can help with branch circuits, feeder runs, garage wiring, shed wiring, equipment circuits, panel work, low-voltage conduit, and general electrical planning.
Your result shows recommended conduit size, conduit fill percentage, total wire area, available fill area, spare area, conductor count, conduit type, run length, and comparison scenarios.
Add the cross-sectional area of all conductors, choose the correct fill percentage, then select a conduit size with enough allowable fill area.
Yes. Ground wires inside the conduit take up space and should be included in fill estimates.
A common planning estimate is 40% fill for more than two conductors, 31% for two conductors, and 53% for one conductor.
No. This calculator is a simplified planning tool. Always verify conduit fill, conductor type, derating, box fill, bend limits, and local code requirements with a qualified electrician.