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Wire Size Calculator
Enter the current, voltage and run length to find the smallest conductor that meets both ampacity and voltage drop.
Wire Size Calculator
Minimum wire size50 A rating · 4.58 V drop (1.9%)
| Size | Ampacity | Voltage drop |
|---|---|---|
| 14 AWG | 20 A | 18.42 V (7.7%) |
| 12 AWG | 25 A | 11.58 V (4.8%) |
| 10 AWG | 35 A | 7.26 V (3%) |
| 8 AWG | 50 A | 4.58 V (1.9%) |
| 6 AWG | 65 A | 2.95 V (1.2%) |
| 4 AWG | 85 A | 1.85 V (0.8%) |
| 3 AWG | 100 A | 1.47 V (0.6%) |
| 2 AWG | 115 A | 1.16 V (0.5%) |
| 1 AWG | 130 A | 0.92 V (0.4%) |
| 1/0 AWG | 150 A | 0.73 V (0.3%) |
| 2/0 AWG | 175 A | 0.58 V (0.2%) |
| 3/0 AWG | 200 A | 0.46 V (0.2%) |
| 4/0 AWG | 230 A | 0.36 V (0.2%) |
| 250 kcmil | 255 A | 0.31 V (0.1%) |
| 300 kcmil | 285 A | 0.26 V (0.1%) |
| 350 kcmil | 310 A | 0.22 V (0.1%) |
| 500 kcmil | 380 A | 0.15 V (0.1%) |
NEC Table 310.16 (75 °C column), 240.4(D) small-conductor limits and Chapter 9 Table 8 resistance. Apply continuous-load (125%), ambient temperature and bundling corrections, and follow your local code and AHJ.
Planning estimates only. Building codes, loads and material specs vary — have a licensed engineer or contractor confirm quantities and safety requirements. Disclaimer
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