Wire Size by Amps: Breaker and Service Guides
Pick your breaker size to see the wire gauge that fits it, why copper and aluminum differ, and how far each size can run before voltage drop becomes a problem. Every answer comes from the same NEC Table 310.16 calculation engine as the wire size calculator, so the numbers match.
Guides by breaker or service size
- 15A What Size Wire for a 15 Amp Circuit? 14 AWG copper. General lighting and light-duty receptacle circuits.
- 20A What Size Wire for a 20 Amp Circuit? 12 AWG copper. Kitchen, bathroom, garage and workshop outlets.
- 30A What Size Wire for a 30 Amp Breaker? 10 AWG copper. Electric dryers, water heaters, 30 A RV outlets.
- 40A What Size Wire for a 40 Amp Breaker? 8 AWG copper. EV chargers up to 32 A, small ranges, heat pumps.
- 50A What Size Wire for a 50 Amp Breaker? 6 AWG copper (8 AWG THHN with 75 °C terminals). Ranges, RV, EV, hot tubs.
- 60A What Size Wire for a 60 Amp Breaker? 6 AWG copper (4 AWG for 60 °C). Subpanels, furnaces, large equipment.
- 100A svc What Size Wire for a 100 Amp Service? 4 AWG copper / 2 AWG aluminum for a house service; larger for subpanels.
- 200A svc What Size Wire for a 200 Amp Service? 2/0 copper / 4/0 aluminum for a house service; larger for subpanels.
Wire size for your situation
Pick the case that matches your circuit to see the smallest wire for that distance, load or charger.
- 100ft What Size Wire for 50 Amps at 100 Feet? 50 A at 100 ft: 6 AWG copper. Sizes from 25 to 200 ft.
- 100ft What Size Wire for 30 Amps at 100 Feet? 30 A at 100 ft: 8 AWG copper. Dryers, water heaters, 30 A RV.
- 100ft What Size Wire for 20 Amps at 100 Feet? 20 A at 100 ft: 8 AWG copper. Sheds, garages and outbuildings.
- EV What Size Wire for an EV Charger? Level 2 chargers from 16 to 48 A: breaker, wire and run length.
- SUB What Size Wire for a Subpanel Feeder? 60 and 100 A feeders to a garage, shed or workshop, by distance.
- 12 V 12V Wire Size Chart: Amps vs Length AWG chart for 10 to 200 A over 5 to 30 ft at 12 V DC.
Wire size for each breaker rating
The table lists the smallest wire for each standard breaker rating. The copper 60 °C column is the one used for NM (Romex) cable and older terminals, and the 75 °C column is the usual choice for modern equipment.
| Breaker | Copper, 75 °C | Copper, 60 °C | Aluminum, 75 °C |
|---|---|---|---|
| 15 A | 14 AWG | 14 AWG | 12 AWG |
| 20 A | 12 AWG | 12 AWG | 10 AWG |
| 25 A | 10 AWG | 10 AWG | 10 AWG |
| 30 A | 10 AWG | 10 AWG | 8 AWG |
| 35 A | 8 AWG | 8 AWG | 8 AWG |
| 40 A | 8 AWG | 8 AWG | 8 AWG |
| 45 A | 8 AWG | 6 AWG | 6 AWG |
| 50 A | 8 AWG | 6 AWG | 6 AWG |
| 60 A | 6 AWG | 4 AWG | 4 AWG |
| 70 A | 4 AWG | 4 AWG | 3 AWG |
| 80 A | 4 AWG | 3 AWG | 2 AWG |
| 90 A | 3 AWG | 2 AWG | 2 AWG |
| 100 A | 3 AWG | — | 1 AWG |
| 110 A | 2 AWG | — | 1/0 AWG |
| 125 A | 1 AWG | — | 2/0 AWG |
| 150 A | 1/0 AWG | — | 3/0 AWG |
| 175 A | 2/0 AWG | — | 4/0 AWG |
| 200 A | 3/0 AWG | — | 250 kcmil |
Calculators
Use the Wire Size Calculator for a full answer with your run length, the Voltage Drop Calculator to check a wire you already have, or the 12V Wire Size Calculator for DC circuits.
Wire size also depends on distance and conditions; use the calculator for your exact run.