Wire gauge chart

Name: Wire gauge chart
Creator: Calculate.diy

The smaller the AWG number, the thicker the wire. In NM-B cable, 14 AWG copper is used on a 15 A breaker, 12 AWG on 20 A and 10 AWG on 30 A. 18 and 16 AWG are for cords and low-voltage wiring only.

Wire gauge chart: diameter, area, the largest breaker for copper in NM-B cable and at 75 °C, and common uses
AWG	Diameter, in.	mm²	Breaker, copper NM-B	Breaker, copper 75 °C	Common use
18 AWG	0.0403	0.823	—	—	Lamp cords and light-duty extension cords
16 AWG	0.0508	1.31	—	—	Light-duty extension cords
14 AWG	0.0641	2.08	15	15	Lighting and general outlet circuits
12 AWG	0.0808	3.31	20	20	Kitchen, bathroom, laundry and garage outlet circuits
10 AWG	0.1019	5.26	30	30	Electric dryer and water heater circuits
8 AWG	0.1285	8.37	40	50	Cooktops and wall ovens
6 AWG	0.1620	13.3	50	60	Electric ranges and EV chargers
4 AWG	0.2043	21.2	70	80	Feeders to sub panels
3 AWG	0.2294	26.7	80	100	Feeders to sub panels and detached buildings
2 AWG	0.2576	33.6	90	110	Feeders to sub panels and detached buildings
1 AWG	0.2893	42.4	110	125	Feeders and service entrance conductors
1/0 AWG	0.3249	53.5	125	150	Service entrance conductors
2/0 AWG	0.3648	67.4	125	175	Service entrance conductors
3/0 AWG	0.4096	85	150	200	Service entrance conductors and large feeders
4/0 AWG	0.4600	107.2	175	225	Service entrance conductors and large feeders

Copper NM-B
Copper 75 °C

Largest breaker for copper wire by AWG size.

How to read the wire gauge chart

Breaker columns give the largest standard breaker the copper wire may be used on: its ampacity, capped by the small-conductor limits for 14, 12 and 10 AWG. Use the NM-B column for Romex cable in a house and the 75 °C column for THHN in conduit when every termination is rated 75 °C. Aluminum wire carries less current at the same size; see the ampacity chart.

Above 4/0, sizes are given in thousands of circular mils (kcmil): 600 kcmil is the largest size on this site.

Download PDF

Calculate instead

Sources

NFPA 70, National Electrical Code (2023): Allowable ampacities of insulated conductors, Table 310.16
NFPA 70, National Electrical Code (2023): Overcurrent protection of small conductors, Section 240.4(D)
NFPA 70, National Electrical Code (2023): Conductor properties, Chapter 9 Table 8

Compared with 8 published documents, last on 2026-11-13

American Wire Group (edition not stated): Allowable Ampacities of Insulated Aluminum or Copper-Clad Aluminum Conductors — Aluminum columns and the 15/25 A aluminum small-conductor limits
Cerrowire (NEC 2017): Ampacity Charts — Copper 60/75/90 °C and aluminum 75/90 °C, 14 AWG to 600 kcmil
LugsDirect (NEC 2020): Ampacities of Insulated Conductors From NEC Table 310.16 — All columns, copper and aluminum, every size on this site
LugsDirect (AWG formula): AWG Wire Chart, kcmil and Metric Wire Sizes — Circular mils, square millimeters and diameters by size
Michigan State University, Biosystems and Agricultural Engineering (NEC edition not stated): Electrical Tech Note 212: Conductor Properties — Conductor area, dc resistance at 75 °C and the K constants
Omni Cable (NEC 2017): NEC Ampacity Data — All columns, copper and aluminum
Southwire (NEC 2023): SPEC 10003, THHN/THWN-2 building wire — 14–10 AWG copper and the 15/20/30 A small-conductor limits
Southwire (NEC 2023): SPEC 45007, aluminum XHHW-2 building wire — Copper small-conductor limits 15/20/30 A

Calculated by Calculate.diy with the method of the National Electrical Code® (NEC®), 2023 edition; not the NEC text. Methodology. For planning only: check local code and use a licensed electrician.