Wire Sizing

⚡ Quick Presets — One-Click Sizing EV Charger 40A (continuous) EV Charger 48A (continuous) EV Charger 50A (continuous) 50A Subpanel 100A Subpanel 200A Service 30A Dryer 40A Range Load Amps (A) System Voltage (V) 120 V 208 V 220 V 240 V 277 V 347 V 480 V 600 V Phase 1Φ Single-Phase 3Φ Three-Phase One-Way Length (ft) Wire Material Copper (Cu) Aluminum (Al) Ambient Temp (°C) Current-Carrying Conductors 1 2-3 4-6 7-9 10-20 21-30 31-40 Continuous load (NEC 210.20(A) — 125% rule) Required for EV chargers, solar PV inverters, and any load expected to run > 3 hours. Conductor — — Breaker (OCPD) — amperes Voltage Drop — — Calculation Details Design amps (NEC 125% if continuous) — Base ampacity (NEC 310.16, 75°C) — Temperature correction (310.15(B)(1)) — Conduit-fill derating (310.15(C)(1)) — Final corrected ampacity — NEC 240.4(B) round-up applied Yes — bumped to match OCPD Enter load values to see the formula. 📊 NEC 310.16 Reference Table — 75°C Column (click to expand) AWG / kcmilCopper (A)Aluminum (A)Ω/1000 ft (Cu) 14 AWG20—3.14 12 AWG25—1.98 10 AWG35—1.24 8 AWG50400.778 6 AWG65500.491 4 AWG85650.308 3 AWG100750.245 2 AWG115900.194 1 AWG1301000.154 1/0 AWG1501200.122 2/0 AWG1751350.0967 3/0 AWG2001550.0766 4/0 AWG2301800.0608 250 kcmil2552050.0515 300 kcmil2852300.0429 350 kcmil3102500.0367 400 kcmil3352700.0321 500 kcmil3803100.0258 600 kcmil4203400.0214 750 kcmil4753850.0171 Source: NFPA 70 — National Electrical Code 2023, Table 310.16 (75°C column, the inspector-favored terminal rating per NEC 110.14(C) for circuits rated 100 A or less). ⚠️ Reference only. Calculations are NEC-aware but final conductor sizing must be verified by a licensed electrician and approved by your local Authority Having Jurisdiction (AHJ). Always follow the latest edition of NFPA 70 — National Electrical Code. TL;DR — What this calculator returns. Enter load amps (or use a preset), system voltage, one-way run length, wire material (copper / aluminum), ambient temperature, and number of current-carrying conductors. The tool returns the smallest NEC Table 310.16 (75 °C column) compliant AWG or kcmil, the corrected ampacity after NEC 310.15(B)(1) temperature and NEC 310.15(C)(1) conduit-fill adjustment, the recommended breaker (NEC 240.6(A) standard OCPD), and the voltage-drop % against the NEC 3 % branch / 5 % combined limits. ...