CircuitCalcs

Free electrical calculators

NEC 2023 · every calculator on its own page · no signup, no account

• Conduit Fill CalculatorNEC 2023 · updates as you type · free, no signup
• Wire Size CalculatorServices and feeders · copper or aluminum · NEC 2023
• Voltage DropCheck a drop, or find the wire size that stays inside your limit
• Motor Branch Circuit CalculatorArticle 430 · conductor, OCPD and EGC
• Motor Feeder CalculatorSeveral motors on one feeder · Article 430
• Dwelling Load — Optional MethodOptional method · 220.82 · NEC 2023
• Dwelling Load — Standard MethodStandard method · Article 220 Part III · NEC 2023
• Adding Load to an Existing Dwelling220.83 · is the existing service big enough?
• Commercial Load CalculationBy occupancy · Article 220 · NEC 2023

Educational reference, not code. Based on NEC (NFPA 70) 2023. Your state or local AHJ may enforce a different edition or amend it — theirs is the one that counts. No NEC text is reproduced here.