Wire Size Calc

About this app

NEC wire size calculator for electricians, apprentices, and electrical engineers. Determine the correct wire gauge (AWG/kcmil) for any circuit using official NEC 2023 ampacity tables and derating factors. Supports continuous and non-continuous loads, copper and aluminum conductors, 6 insulation types, and both conduit and free air installations. No internet required - works 100% offline on the job site. FEATURES: - Continuous and non-continuous load sizing (125% factor) - 5 voltage presets: 120V, 208V, 240V, 277V, 480V - Single-phase and three-phase support - Copper and aluminum conductors: 14 AWG through 2000 kcmil - AWG and mm² (metric) display toggle - 6 insulation types: THHN, THW, TW, XHHW-2, NM-B, USE-2 - Conduit and free air installation methods - Temperature correction factor (NEC 310.15(B)(1)) - Conduit fill adjustment factor (NEC 310.15(C)(1)) - Termination rating check (60°C / 75°C per NEC 110.14(C)) - Overcurrent protection sizing (NEC 240.4(D)) - Optional voltage drop check when distance is provided - PASS/FAIL indicator for quick compliance check NEC REFERENCES: - Table 310.16 - Ampacity in conduit/raceway - Table 310.17 - Ampacity in free air - Table 310.15(B)(1) - Temperature correction factors - Table 310.15(C)(1) - Conduit fill adjustment factors - NEC 110.14(C) - Termination temperature limits - NEC 240.4(D) - Small conductor overcurrent protection PRO FEATURES (one-time purchase): - No ads - Save calculation history - Export calculations as PDF reports - Dark theme support BUILT FOR THE JOB SITE: This app is designed by electricians, for electricians. Enter your circuit parameters, get the recommended wire size instantly - no complicated menus or unnecessary features. One-hand operation, instant results. HOW IT WORKS: 1. Enter load current in amps 2. Select load type (continuous or non-continuous) 3. Choose voltage, phase, conductor material, insulation type 4. Set installation method and ambient temperature 5. Get recommended wire size with full derating breakdown The calculator automatically applies: - 125% continuous load factor - Temperature correction for ambient conditions - Conduit fill adjustment for conductor count - Termination temperature limit verification - Standard breaker size selection PERFECT FOR: - Licensed electricians - Electrical apprentices - Electrical engineers and designers - Electrical contractors - NEC code exam preparation - Journeyman and master electrician exams OFFLINE & PRIVACY: - Works 100% offline - no internet needed - No account required - No data collection - Your calculations stay on your device Simplify your wire sizing on the job site.

What's new: • AWG / mm² unit toggle in Settings — show wire sizes with their metric cross-section (e.g. 12 AWG · 3.31 mm²) • Metric labels apply everywhere: result card, history and PDF export • NEC sizing math is unchanged — mm² is the exact area of the AWG conductor • Bug fixes and stability improvements Thanks for using ElecTools! Send feedback to support@tradetools.dev.

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1. First observed Aug 23, 2026 · 2:42 AM $0.99