Is a higher AWG number thicker or thinner?

Thinner. AWG is a reverse scale — the number increases as the wire gets thinner. AWG 10 is thicker than AWG 20.

What is AWG 10 in mm²?

AWG 10 has a nominal cross-sectional area of 5.26 mm² and a diameter of 2.588 mm (0.1019 in).

How much does gauge change current capacity?

Roughly tenfold per ten gauge numbers, because the cross-sectional area changes by about a factor of ten. AWG 10 carries roughly ten times the current of AWG 20 under the same conditions.

What does 2/0 or 4/0 mean?

Gauges larger than 0 are written as fractions — 2/0 (also 00) and 4/0 (also 0000). These are thicker than AWG 0, with 4/0 the thickest in common use at 11.684 mm diameter and 107 mm².

Does AWG apply to stranded wire?

Yes. A stranded conductor is specified by its total equivalent AWG, which refers to the total copper cross-section. The overall diameter is larger than the equivalent solid gauge because of the air gaps and the stranding lay.

Why is resistance listed per metre and per foot?

North American work is usually calculated in feet and metric work in metres. Both are given so voltage-drop calculations can be done in either system without conversion.

Wire Gauge (AWG) Chart

American Wire Gauge to diameter, cross-sectional area and DC resistance — AWG 0000 through 40, in metric and imperial units, with a searchable table and a cross-section converter.

Page last changed 2026-10-19 · based on ASTM B258-18

Quick Answer

AWG is a reverse logarithmic scale: a larger gauge number means a thinner wire. Decreasing the AWG number by 10 multiplies the cross-sectional area — and therefore the current capacity — by roughly 10. AWG 10 is about 5.26 mm² and AWG 20 is about 0.52 mm².

Find a gauge

American Wire Gauge (AWG) Table

AWG^[1]	Diameter in^[1]	Diameter mm^[2]	Area kcmil^[1]	Area mm²^[2]	Resistance mΩ/m^[3]	Resistance mΩ/ft^[3]
0000 (4/0) #	0.46	11.684	212	107	0.1608	0.04901
000 (3/0) #	0.4096	10.405	168	85.0	0.2028	0.06180
00 (2/0) #	0.3648	9.266	133	67.4	0.2557	0.07793
0 (1/0) #	0.3249	8.251	106	53.5	0.3224	0.09827
1 #	0.2893	7.348	83.7	42.4	0.4066	0.1239
2 #	0.2576	6.544	66.4	33.6	0.5127	0.1563
3 #	0.2294	5.827	52.6	26.7	0.6465	0.1970
4 #	0.2043	5.189	41.7	21.2	0.8152	0.2485
5 #	0.1819	4.621	33.1	16.8	1.028	0.3133
6 #	0.162	4.115	26.3	13.3	1.296	0.3951
7 #	0.1443	3.665	20.8	10.5	1.634	0.4982
8 #	0.1285	3.264	16.5	8.37	2.061	0.6282
9 #	0.1144	2.906	13.1	6.63	2.599	0.7921
10 #	0.1019	2.588	10.4	5.26	3.277	0.9989
11 #	0.0907	2.305	8.23	4.17	4.132	1.260
12 #	0.0808	2.053	6.53	3.31	5.211	1.588
13 #	0.072	1.828	5.18	2.62	6.571	2.003
14 #	0.0641	1.628	4.11	2.08	8.286	2.525
15 #	0.0571	1.45	3.26	1.65	10.45	3.184
16 #	0.0508	1.291	2.58	1.31	13.17	4.016
17 #	0.0453	1.15	2.05	1.04	16.61	5.064
18 #	0.0403	1.024	1.62	0.823	20.95	6.385
19 #	0.0359	0.912	1.29	0.653	26.42	8.051
20 #	0.032	0.812	1.02	0.518	33.31	10.15
21 #	0.0285	0.723	0.810	0.410	42.00	12.80
22 #	0.0253	0.644	0.642	0.326	52.96	16.14
23 #	0.0226	0.573	0.509	0.258	66.79	20.36
24 #	0.0201	0.511	0.404	0.205	84.22	25.67
25 #	0.0179	0.455	0.320	0.162	106.2	32.37
26 #	0.0159	0.405	0.254	0.129	133.9	40.81
27 #	0.0142	0.361	0.202	0.102	168.9	51.47
28 #	0.0126	0.321	0.160	0.0810	212.9	64.90
29 #	0.0113	0.286	0.127	0.0642	268.5	81.84
30 #	0.01	0.255	0.101	0.0509	338.6	103.2
31 #	0.0089	0.227	0.0797	0.0404	426.9	130.1
32 #	0.008	0.202	0.0632	0.0320	538.3	164.1
33 #	0.0071	0.18	0.0501	0.0254	678.8	206.9
34 #	0.0063	0.16	0.0398	0.0201	856.0	260.9
35 #	0.0056	0.143	0.0315	0.0160	1079	329.0
36 #	0.005	0.127	0.0250	0.0127	1361	414.8
37 #	0.0044	0.113	0.0198	0.0100	1716	523.1
38 #	0.004	0.101	0.0157	0.00797	2164	659.6
39 #	0.0035	0.0897	0.0125	0.00632	2729	831.8
40 #	0.0031	0.0799	0.00989	0.00501	3441	1049

Diameter and area are for solid copper conductors. Resistance is DC at 20 °C. Values are given to the precision published in the source standard; small rounding differences of up to about 2% may appear between the inch and millimetre columns.

Cross-Section (mm²) to Nearest AWG

Cross-sectional area (mm²)

How the AWG Scale Works

AWG is defined so that two consecutive gauges differ in diameter by a fixed ratio. The scale is inverse — the number increases as the wire gets thinner — and it runs from 0000 (written 4/0) at the thick end to 40 and beyond at the thin end.

The defining relationship for gauge n is:

diameter (inch) = 0.005 × 92^{(36 − n)/39}

The practical consequence of the ratio 92^1/39 ≈ 1.1229 is that a change of ten gauge numbers changes the area by about ten times. That is why a 10 AWG wire carries roughly ten times the current of a 20 AWG wire.

AWG vs mm² — Why Both Are Used

North American practice sizes conductors by AWG; most of the rest of the world sizes them by cross-sectional area in mm². The two systems do not convert exactly, because AWG defines a diameter while mm² defines an area. Common approximate equivalents:

Choosing a Wire Gauge

Gauge selection is driven by three constraints, and the binding one is usually temperature rise rather than voltage drop:

Current capacity (ampacity) — the gauge must carry the design current without exceeding the insulation's temperature rating. Ampacity rises with area, and also depends on insulation type, ambient temperature and how many conductors are bundled.
Voltage drop — over long runs the resistance in the table above produces a voltage drop that may exceed the allowable percentage before the wire's ampacity is reached. This is what forces a larger gauge on long circuits.
Mechanical strength — very fine gauges are fragile and are limited by handling and termination rather than electrically.

The resistance values in the table let you calculate voltage drop directly: V_drop = 2 × length × current × resistance per unit length for a single-phase two-wire circuit.

Frequently Asked Questions

Is a higher AWG number thicker or thinner?: Thinner. AWG is a reverse scale — the number increases as the wire gets thinner. AWG 10 is thicker than AWG 20.
What is AWG 10 in mm²?: AWG 10 has a nominal cross-sectional area of 5.26 mm² and a diameter of 2.588 mm (0.1019 in).
How much does gauge change current capacity?: Roughly tenfold per ten gauge numbers, because the cross-sectional area changes by about a factor of ten. AWG 10 carries roughly ten times the current of AWG 20 under the same conditions.
What does 2/0 or 4/0 mean?: Gauges larger than 0 are written as fractions — 2/0 (also 00) and 4/0 (also 0000). These are thicker than AWG 0, with 4/0 the thickest in common use at 11.684 mm diameter and 107 mm².
Does AWG apply to stranded wire?: Yes. A stranded conductor is specified by its total equivalent AWG, which refers to the total copper cross-section. The overall diameter is larger than the equivalent solid gauge because of the air gaps and the stranding lay.
Why is resistance listed per metre and per foot?: North American work is usually calculated in feet and metric work in metres. Both are given so voltage-drop calculations can be done in either system without conversion.

Value Sources

References and calculation methods used for this page are listed below. Numbered markers connect table columns where present. A reference listing does not itself establish that every value has been independently checked.

#	Source	Type	Revision / method
[1]	ASTM B258 — Standard Specification for Standard Nominal Diameters and Cross-Sectional Areas of AWG Sizes	reference	ASTM B258-18 — source
[2]	Millimetre and area conversion	derived	Inch values × 25.4. Area in mm² computed as π/4 × d², then rounded to 3 significant figures as published.
[3]	Copper DC resistance at 20 °C	derived	ρ = 1.7241 × 10⁻⁸ Ω·m (IACS annealed copper) applied to the nominal cross-sectional area from ASTM B258. Does not include stranding factor.

Data Sources

Standard	Revision	What it covers on this page
ASTM B258 — Standard Specification for Standard Nominal Diameters and Cross-Sectional Areas of AWG Sizes	ASTM B258-18	nominal conductor diameter and cross-sectional area for each AWG size

Verification scope

No page-specific independent source review is recorded here. The listed references and formulas explain the basis of the compilation; automated consistency checks do not verify the original sources or establish product conformity.

Nominal values as published in the referenced standard. Manufacturing tolerances apply.

Accuracy and use. Use the source notes and recorded verification scope above to assess each value. Calculated values follow the stated derivations; compilation values may lack a confirmed original document or product condition. No warranty, express or implied, is made as to the accuracy or completeness of this information, and no liability is accepted for any loss or damage arising from its use. Engineering reference data is provided for guidance in preliminary work — before a value is used for design, fabrication or acceptance testing, verify it against the current revision of the governing standard and against your own inspection. The user assumes all risk and responsibility in connection with the use of this information.

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Plain text

Engineering Reference. "Wire Gauge (AWG) Chart." https://refmanual.com/charts/wire-gauge-awg/ (accessed 2026-10-19). Data from ASTM B258 — Standard Specification for Standard Nominal Diameters and Cross-Sectional Areas of AWG Sizes, ASTM B258-18.

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@misc{wire-gauge-awg,
  title        = {Wire Gauge (AWG) Chart},
  author       = {{Engineering Reference}},
  howpublished = {\url{https://refmanual.com/charts/wire-gauge-awg/}},
  note         = {Accessed: 2026-10-19},
  source       = {ASTM B258 — Standard Specification for Standard Nominal Diameters and Cross-Sectional Areas of AWG Sizes, ASTM B258-18}
}

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TY  - ELEC
TI  - Wire Gauge (AWG) Chart
AU  - Engineering Reference
PB  - Engineering Reference
UR  - https://refmanual.com/charts/wire-gauge-awg/
PY  - 2026
DA  - 2026-10-19
N1  - Source: ASTM B258 — Standard Specification for Standard Nominal Diameters and Cross-Sectional Areas of AWG Sizes, ASTM B258-18
ER  -

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