AWG to mm² Conversion Chart & Calculator

Convert American Wire Gauge (AWG) to metric wire sizes. Select any gauge to see the conductor diameter in mm, cross-sectional area in mm², and the nearest IEC standard metric size — or enter a metric size to find the closest AWG.

AWG to mm² Converter

Select AWG or kcmil Size

Reverse: mm² to AWG

Cross-Section (mm²)

Note: AWG and metric (IEC) sizes never match exactly. Always verify ampacity against the applicable electrical code (NEC or IEC) before substituting one for the other.

AWG to mm² Conversion Chart

Complete conversion table from 30 AWG to 4/0 AWG. Diameters are calculated from the exact AWG formula d = 0.127 × 92^(36−n)/39; areas are π/4 × d². The last column shows the nearest IEC 60228 standard metric conductor size — not an exact equivalent.

AWG	Diameter (mm)	Area (mm²)	Nearest Metric Size
30 AWG	0.255	0.051	—
29 AWG	0.286	0.064	—
28 AWG	0.321	0.081	—
27 AWG	0.361	0.102	—
26 AWG	0.405	0.129	—
25 AWG	0.455	0.162	—
24 AWG	0.511	0.205	—
23 AWG	0.573	0.258	—
22 AWG	0.644	0.326	—
21 AWG	0.723	0.410	≈ 0.5 mm²
20 AWG	0.812	0.518	≈ 0.5 mm²
19 AWG	0.912	0.653	≈ 0.75 mm²
18 AWG	1.024	0.823	≈ 0.75 mm²
17 AWG	1.150	1.04	≈ 1 mm²
16 AWG	1.291	1.31	≈ 1.5 mm²
15 AWG	1.450	1.65	≈ 1.5 mm²
14 AWG	1.628	2.08	≈ 2.5 mm²
13 AWG	1.828	2.62	≈ 2.5 mm²
12 AWG	2.053	3.31	≈ 4 mm²
11 AWG	2.305	4.17	≈ 4 mm²
10 AWG	2.588	5.26	≈ 6 mm²
9 AWG	2.906	6.63	≈ 6 mm²
8 AWG	3.264	8.37	≈ 10 mm²
7 AWG	3.665	10.55	≈ 10 mm²
6 AWG	4.115	13.30	≈ 16 mm²
5 AWG	4.621	16.77	≈ 16 mm²
4 AWG	5.189	21.15	≈ 25 mm²
3 AWG	5.827	26.67	≈ 25 mm²
2 AWG	6.544	33.63	≈ 35 mm²
1 AWG	7.348	42.41	≈ 50 mm²
1/0 AWG	8.251	53.48	≈ 50 mm²
2/0 AWG	9.266	67.43	≈ 70 mm²
3/0 AWG	10.405	85.03	≈ 95 mm²
4/0 AWG	11.684	107.2	≈ 120 mm²

Quick reference for the most common building-wire sizes: 14 AWG = 1.628 mm ∅, 2.08 mm² (≈ 2.5 mm²) • 12 AWG = 2.053 mm, 3.31 mm² (≈ 4 mm²) • 10 AWG = 2.588 mm, 5.26 mm² (≈ 6 mm²) • 8 AWG = 3.264 mm, 8.37 mm² (≈ 10 mm²) • 6 AWG = 4.115 mm, 13.30 mm² (≈ 16 mm²).

kcmil to mm² Conversion (Above 4/0 AWG)

Wires larger than 4/0 AWG are sized in kcmil (thousand circular mils, formerly written MCM) in North America. One circular mil is the area of a circle one mil (0.001 inch) in diameter. The conversion to metric is a simple multiplication:

Formula: mm² = kcmil × 0.5067

Size (kcmil)	Area (mm²)	Nearest Metric Size
250 kcmil	126.7	≈ 120 mm²
300 kcmil	152.0	≈ 150 mm²
350 kcmil	177.3	≈ 185 mm²
400 kcmil	202.7	≈ 185 mm²
500 kcmil	253.4	≈ 240 mm²
600 kcmil	304.0	≈ 300 mm²
750 kcmil	380.0	≈ 400 mm²
1000 kcmil	506.7	≈ 500 mm²
1250 kcmil	633.4	≈ 630 mm²
1500 kcmil	760.1	≈ 800 mm²
1750 kcmil	886.7	≈ 800 mm²
2000 kcmil	1013.4	≈ 1000 mm²

How AWG Works

American Wire Gauge is a logarithmic scale— smaller gauge numbers mean larger wires. The exact conductor diameter for any AWG number n is:

Diameter: d(mm) = 0.127 × 92^(36−n)/39

Area: mm² = π/4 × d²

For sizes beyond 0: 1/0 = 0, 2/0 = −1, 3/0 = −2, 4/0 = −3

Because the scale is logarithmic, two handy rules of thumb follow directly from the formula:

Every 3-gauge step doubles the cross-sectional area. For example, 12 AWG (3.31 mm²) has roughly twice the area of 15 AWG (1.65 mm²), and 4/0 AWG (107.2 mm²) has about twice the area of 1 AWG (42.4 mm²).
Every 6-gauge step doubles the diameter. For example, 6 AWG (4.115 mm) is about twice the diameter of 12 AWG (2.053 mm) — and therefore four times the area.
A 10-gauge step multiplies the area by almost exactly 10 — 10 AWG (5.26 mm²) has ten times the area of 20 AWG (0.518 mm²).

AWG vs. Metric (IEC) Wire Sizes

The rest of the world sizes conductors by cross-sectional area using the IEC 60228 standard series: 1.5, 2.5, 4, 6, 10, 16, 25, 35, 50, 70, and 95 mm² (continuing to 120, 150, 185, 240 mm² and beyond). These metric sizes never map exactly to AWG sizes.For example, 2.5 mm² sits between 14 AWG (2.08 mm²) and 12 AWG (3.31 mm²), and 4 mm² is about 21% larger than 12 AWG.

Because the sizes differ — and because North American (NEC) and international (IEC) ampacity tables use different insulation temperature ratings, installation methods, and derating rules — never substitute a metric wire for an AWG wire (or vice versa) based on this chart alone. Always verify the conductor's ampacity against the applicable electrical code for your installation. Our wire ampacity chart and wire sizing calculator cover the NEC side of that check.

Frequently Asked Questions

How do you convert AWG to mm²?

First find the wire diameter in mm using the formula d = 0.127 × 92^(36−n)/39, where n is the AWG number (use 0 for 1/0, −1 for 2/0, −2 for 3/0, −3 for 4/0). Then calculate the cross-sectional area: mm² = π/4 × d². For example, 12 AWG has a diameter of 2.053 mm, so its area is π/4 × 2.053² = 3.31 mm².

What is 12 AWG in mm²?

12 AWG is 3.31 mm² in cross-sectional area, with a conductor diameter of 2.053 mm. The nearest standard metric wire size is 4 mm². Note that 4 mm² is about 21% larger than 12 AWG, so the two are not interchangeable without checking ampacity requirements.

What is 2.5 mm² in AWG?

2.5 mm² falls between 14 AWG (2.08 mm²) and 12 AWG (3.31 mm²). The closest single gauge is 13 AWG (2.62 mm²), but since 13 AWG is rarely used, 2.5 mm² is most commonly compared to 14 AWG. Because 2.5 mm² is about 20% larger than 14 AWG, always verify ampacity against the applicable code before substituting.

What is 10 AWG in mm²?

10 AWG is 5.26 mm² in cross-sectional area, with a conductor diameter of 2.588 mm. The nearest standard metric size is 6 mm². As with all AWG-to-metric comparisons, the metric size is slightly different, so confirm the ampacity rating for your application.

What does kcmil mean?

kcmil stands for thousand circular mils (formerly written MCM). One circular mil is the area of a circle with a diameter of one mil (0.001 inch). Wires larger than 4/0 AWG are sized in kcmil in North America. To convert kcmil to mm², multiply by 0.5067 — for example, 250 kcmil = 126.7 mm², and 500 kcmil = 253.4 mm².

Is AWG the same as mm?

No. AWG (American Wire Gauge) is a logarithmic gauge number where smaller numbers mean larger wires, while mm and mm² are direct metric measurements of diameter and cross-sectional area. There is no simple linear relationship — you must use the AWG formula or a conversion chart. For example, 14 AWG is not 14 mm; it is 1.628 mm in diameter and 2.08 mm² in area.