NEC Electrical Load Calculator

NEC Load Calculator sizes services, feeders, motors, branch circuits, panels and cable tray using the 2023 NEC — and every result shows the article citation, the demand factor table used, and the step-by-step math. Export any calculation as a PDF for permit submission. Built for electricians, electrical contractors, engineers and inspectors who need an answer they can check against the code book — not just a final number. WHAT YOU CAN CALCULATE • Residential service size — dwelling unit load calculation, standard method (NEC 220.40–220.55) and optional method (220.82). General lighting, small appliance and laundry circuits, fixed appliances, dryer, ranges and cooking equipment, HVAC, with 230.79(C) service minimums. • Commercial feeder and service — NEC 220.12, 220.44, 220.60 and 430.24. Lighting, receptacles, motors, HVAC units, sign circuits and demand factors. • Branch circuit wire and breaker size — conductor and OCPD sizing per NEC 210.19, 310.12 and 310.15(B)(1)(a). Continuous loads, conduit fill derating and ambient temperature correction, 120V through 480V. • Motor circuits — conductor, overload and OCPD sizing per NEC 430.22, 430.32 and 430.52, with full motor table lookups by horsepower, voltage and phase. • Panel schedule — circuit-by-circuit panel editor with phase balance, loading percentage and imbalance per NEC 220.40 and 220.87. • Cable tray — tray fill and ampacity derating per NEC 392.22(A) and 392.80(A). Ventilated trough and solid-bottom trays, small-cable fill-area limits and the 90% width rule for large cables. PANEL LAYOUT FROM YOUR LOAD CALC Turn a load calculation into a panel layout: circuit numbers, breaker sizes, two-pole spans and spare spaces, arranged the way a real panelboard is wired. Then fine-tune labels, phase assignment or breaker sizes in the Panel Schedule editor. SHOW YOUR WORK Every result lists the NEC article, the demand table and each step of the math, so you can verify it, explain it to an inspector or teach it to an apprentice. PDF REPORTS Export any result as a PDF for permits, job files or client records. INTERNATIONAL VOLTAGES Supports 220/127V and 440/254V systems (including 127V, 220V, 254V and 440V circuits) alongside standard US voltages, with a reminder to verify against NOM-001-SEDE in Mexico. IPHONE, IPHONE DUO AND IPAD Full-width layouts on iPad and the unfolded iPhone Duo, in any orientation. FREE AND PRO Residential and Branch Circuit calculations are free. A one-time Pro purchase unlocks Commercial, Motor, Panel Schedule, Cable Tray and PDF export. No subscription.