Wire Gauges

Reference data and engineering information about wire gauges for electrical applications.

wiregauges

Overview

The American Wire Gauge (AWG) system—also known as Brown and Sharpe (B&S) Wire Gauge—is the standard method for denoting wire diameter in North America. Gauge numbers are assigned to the bare conductor diameter with insulation removed. A higher AWG number corresponds to a thinner wire: typical household wiring uses AWG 12 or 14, while telephone wire commonly uses AWG 22, 24, or 26.

Because of the small air gaps between strands, a stranded wire with the same current-carrying capacity and resistance as a solid conductor will always have a slightly larger overall diameter. The tables below cover single, solid, round conductors unless otherwise noted.

Key Formulas

Resistance per length

$R = \frac{\rho \cdot L}{A}$

Where $\rho$ is the conductor resistivity, $L$ is the length, and $A$ is the cross-sectional area.

Voltage drop (single-phase, one-way run)

$\Delta V = \frac{2 \cdot I \cdot \rho \cdot L}{A}$

Current derating for elevated ambient temperature

$I_{\text{corrected}} = I_{\text{rated}} \times C_f$

Where $C_f$ is the temperature correction factor from the table below.

Variables

Symbol	Description	Unit
$R$	Electrical resistance	Ω
$\rho$	Electrical resistivity	Ω·m
$L$	Conductor length	m
$A$	Cross-sectional area	mm²
$I$	Current	A
$\Delta V$	Voltage drop	V
$C_f$	Temperature correction factor	—

AWG Dimensions and Resistance

16 rows

AWG dimensions and DC resistance per 1000 m. Resistivity based on Cu = 1.724 × 10⁻⁸ Ω·m and Al = 2.65 × 10⁻⁸ Ω·m.
AWG	Diameter(mm)	Cross Section(mm²)	Resistance Cu(Ω/1000m)	Resistance Al(Ω/1000m)
40	0.08	0.005	3448	5300
36	0.13	0.013	1326	2038
32	0.2	0.031	556	855
28	0.33	0.08	216	331
26	0.41	0.13	133	204
24	0.51	0.2	88	133
22	0.64	0.33	54.3	83.4
20	0.81	0.52	33.9	52.1
18	1.02	0.82	21.4	32.9
16	1.29	1.31	13.5	20.7
14	1.63	2.08	8.45	13
12	2.05	3.31	5.31	8.17
10	2.59	5.26	3.34	5.13
8	3.26	8.37	2.1	3.23
6	4.11	13.3	1.32	2.03
4	5.19	21.2	0.83	1.27

Source: engineeringtoolbox.com

AWG Diameter and Cross-Section Area

Copper and Aluminum Wire Resistance by AWG

Current Ratings — PVC-Insulated Copper Cable

Current ratings below apply to PVC-insulated single and multicore wiring cables at ambient temperature up to 30 °C and voltage up to 1000 V. Actual capacity depends on installation method, enclosure, conductor temperature, and ambient conditions.

11 rows

Typical max current ratings for PVC-insulated copper conductors at ≤30 °C ambient, ≤1000 V.
AWG	Cross Section(mm²)	Single Core(A)	Multicore ≤3(A)	Multicore 4-6(A)
24	0.2	3.5	2	1.5
22	0.33	5	3.5	2.5
20	0.52	7	5	3.5
18	0.82	10	7	5
16	1.31	15	10	7
14	2.08	20	15	10
12	3.31	25	20	15
10	5.26	35	25	20
8	8.37	50	35	25
6	13.3	70	50	35
4	21.2	95	70	50

Source: engineeringtoolbox.com

Temperature Correction Factors

When ambient temperature exceeds 30 °C, multiply the rated current by the applicable correction factor.

3 rows

Derating factors for PVC-insulated cables at elevated ambient temperatures.
Ambient Temperature	Correction Factor
31 – 40 °C	0.82
41 – 45 °C	0.71
45 – 50 °C	0.58

Source: engineeringtoolbox.com

AWG Resistance Calculator

Wire Resistance

AWG Size

One-Way Length(m)

Voltage Drop (Single Phase DC)

Load Current(A)

Wire Resistance(Ω)

Unit Converter

Wire Gauge Unit Converter

Diameter(mm)

Area(mm2)

Resistance(ohm/km)

Restored Original Source Tables

The following tables are restored from the original source page to preserve the complete reference data.

AWG - American Wire Gauge Current Ratings

37 rows

AWG - American Wire Gauge Current Ratings
Single Core	Multicore	Multicore	Multicore	Multicore	Multicore	Typical Max. Current Load Ratings - Copper (amps) 1)	Typical Max. Current Load Ratings - Copper (amps) 1)	Typical Max. Current Load Ratings - Copper (amps) 1)	Typical Max. Current Load Ratings - Copper (amps) 1)	Typical Max. Current Load Ratings - Copper (amps) 1)	Typical Max. Current Load Ratings - Copper (amps) 1)
up to 3 cores	4 - 6 cores	7 - 24 cores	25 - 42 cores	43 and above
40	0.08	.	0.005	3448	5300
39	0.09	.	0.0064	2693	4141
38	0.1	0.004	0.0078	2210	3397
37	0.11	0.0045	0.0095	1810	2789
36	0.13	0.005	0.013	1326	2038
35	0.14	0.0056	0.015	1120	1767
34	0.16	0.0063	0.02	862	1325
33	0.18	0.0071	0.026	663	1019
32	0.2	0.008	0.031	556	855
30	0.25	0.01	0.049	352	541
28	0.33	0.013	0.08	216	331
27	0.36	0.014	0.096	180	276
26	0.41	0.016	0.13	133	204
25	0.45	0.018	0.16	108	166
24	0.51	0.02	0.2	88	133	3.5	2	1.6	1.4	1.2	1
22	0.64	0.025	0.33	52	80	5	3	2.4	2.1	1.8	1.5
20	0.81	0.032	0.5	34	53	6	5	4	3.5	3	2.5
18	1	0.04	0.82	21	32	9.5	7	5.6	4.9	4.2	3.5
16	1.3	0.051	1.3	13	20	15	10	8	7	6	5
14	1.6	0.064	2.1	8.2	13	24	15	12	10	9	7.5
13	1.8	0.072	2.6	6.6	10
12	2.1	0.081	3.3	5.2	8	34	20	16	14	12	10
10	2.6	0.1	5.3	3.3	5	52	30	24	21	18	15
8	3.3	0.13	8.3	2.1	3.2	75	40	32	28	24	20
6	4.1	0.17	13.3	1.3	2	95	55	44	38	33	27
4	5.2	0.2	21.2	0.81	1.3	120	70	56	49	42	35
3			26.7	0.65	0.99	154	80	64	56	48	40
2	6.5	0.26	33.6	0.51	0.79	170	95	76	66	57	57
1	7.4	0.29	42.4	0.41	0.63	180	110	88	77	66	55
0 (1/0)	8.3	0.33	53.5	0.32	0.5	200
00 (2/0)	9.3	0.37	67.4	0.26	0.39	225
000 (3/0)	10.4	0.41	85	0.2	0.32	275
0000 (4/0)	11.7	0.46	107	0.16	0.25	325
250			127			345
300			152			390
400			178			415

Source: engineeringtoolbox.com

Original Source Images

The following original source images are preserved to avoid losing visual reference material. When an image contains chart or tabular data, its extracted values are represented in the page tables, calculators, or interactive charts; remaining images are retained as visual source references.

American Wire Gauge - AWG, Imperial and Metric Units American Wire Gauge - AWG electrical resistance copper aluminum awg wire

Engineering Notes

Stranded vs. solid conductors. A stranded wire that matches the resistance and ampacity of a solid conductor will have a slightly larger outside diameter due to interstitial air space.
Longer runs require larger wire. To limit voltage drop on long circuits, reduce the AWG number (increase conductor area). A common engineering guideline is to keep voltage drop under 3% for branch circuits and 5% total (feeder plus branch).
Bundled conductors. When multiple current-carrying conductors share a conduit or bundle, additional derating beyond the temperature factors above is required per NEC/NFPA 70 or local codes.
Aluminum conductors. Aluminum wire carries roughly 61% of the current capacity of equivalent copper due to its higher resistivity (2.65 × 10⁻⁸ Ω·m vs. 1.724 × 10⁻⁸ Ω·m). Contact resistance at termination points is also higher, requiring special connectors.
Always consult manufacturer data. Ratings vary with insulation type (PVC, XLPE, EPR), conductor temperature rating, and installation method. The values here are typical reference figures only.

References

Original Source — Engineering ToolBox: Wire Gauges

Source: engineeringtoolbox.com