WireSpan: Conduit Fill Calc

NEC 2023 (NFPA 70) included with no extra charge and no subscription. Voltage drop, wire size, conduit and box fill with visible formulas and PASS/FAIL results.

WireSpan is a fast electrical calculator built on the NEC 2023 (NFPA 70) reference tables. It is made for electricians, apprentices, and contractors who need answers they can stand behind on the job site.

Run everyday math in seconds, then tap Show Work to see every formula and NEC 2023 table reference behind the result. No black box answers. No guessing.

Free tools include Ohm's Law, Voltage Drop for single or three phase copper or aluminum runs with instant PASS/FAIL, and a Unit Converter for AWG to mm², feet to meters, and inches to mm.

WireSpan Pro is a one time purchase that unlocks Wire Size with minimum conductor AWG, ampacity, conductor count, and ambient derating, Conduit Fill for EMT, PVC, and RMC with PASS/FAIL, Box Fill with NEC 314.16 volume checks, saved history for your last 100 calculations, PDF export with inputs, result, formulas, and disclaimer, and iCloud sync across your devices.

Every result shows the math and the NEC 2023 reference. PASS/FAIL badges cover voltage drop, conduit fill, and box fill. The app has large buttons, dark mode, and works fully offline. You can copy any result with its formula in one tap.

The current NEC 2023 tables are built in, so you do not pay extra to unlock the latest code. Other pro electrical apps charge around $40 a year or make you buy each code edition separately. WireSpan Pro is a single one time purchase that unlocks every Pro tool forever. No renewals. No surprises.

WireSpan is a reference tool. Always verify results against the applicable National Electrical Code®, local amendments, and the authority having jurisdiction. WireSpan is not affiliated with NFPA, NEC®, or any manufacturer.