AWG to mm2 Converter

Convert AWG or kcmil to mm2, or mm2 to the nearest AWG, and see the next standard metric size up and down.

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To convert AWG to mm2, take the gauge’s diameter from the AWG formula and work out the area of that circle: 12 AWG is 3.309 mm², 10 AWG is 5.261 mm² and 4/0 AWG is 107.2 mm². This converter does it for every size from 30 AWG to 2000 kcmil and also runs the other way, from a metric cross-section to the nearest AWG. Because the two systems almost never line up, it lists the standard IEC 60228 metric sizes just above and just below an AWG wire, or the AWG sizes either side of a metric cable, with the resistance difference of each in percent. That tells you at a glance whether a substitute conductor would carry the load with more or less voltage drop than the one specified.

How to use the AWG to mm² converter

Open Convert and choose “AWG / kcmil to mm²” to start from a gauge, or “mm² to AWG” to start from a metric cross-section.
In the first mode, pick a value in the AWG or kcmil size list. It runs from 30 AWG to 2000 kcmil, including the small sizes used in electronics and data cable.
In the second mode, type the Cross-section (mm²), for example 1.5, 2.5, 4, 6, 10 or 16. Any value is accepted; the tool warns when it is not a standard IEC 60228 size.
Read the main result: Cross-section for an AWG input, or Nearest AWG size with its Area of the nearest AWG and the Difference for a metric input.
Check the neighbouring sizes. For an AWG input, Metric size at or above and Metric size at or below each come with a resistance comparison. For a metric input, Next AWG size up and Next AWG size down do the same.
The Diameter (solid), Diameter (inches), Circular mils and kcmil (MCM) rows give the other ways the same wire is described.
Look at the Neighbouring sizes table for the three gauges on each side with their metric equivalents.

The example buttons above the form load 14, 12, 10 and 4/0 AWG, 2.5 mm² and 6 mm². Copy result, Copy link and Print / save as PDF keep the conversion, and Reset returns to 12 AWG.

How do you convert AWG to mm²?

Find the diameter from the gauge number, then the area of a circle with that diameter. The AWG definition is d = 0.127 mm × 92^((36 − n) ÷ 39), and the area is A = π ÷ 4 × d². For 12 AWG that gives a 2.0525 mm diameter and 3.3088 mm², or 6,529.95 circular mils.

Sizes above 4/0 AWG are named in kcmil, so the step is simpler: 1 kcmil = 0.5067075 mm². 250 kcmil is 126.7 mm² and 500 kcmil is 253.4 mm². Common gauges and their nearest IEC 60228 sizes, as the tool returns them:

AWG	Area (mm²)	Metric size at or above	Its resistance vs the AWG	Metric size at or below
18	0.823	1 mm²	−17.7 %	0.75 mm²
16	1.309	1.5 mm²	−12.75 %	1 mm²
14	2.081	2.5 mm²	−16.76 %	1.5 mm²
12	3.309	4 mm²	−17.28 %	2.5 mm²
10	5.261	6 mm²	−12.31 %	4 mm²
8	8.366	10 mm²	−16.34 %	6 mm²
6	13.30	16 mm²	−16.86 %	10 mm²
4	21.15	25 mm²	−15.4 %	16 mm²

What AWG is 2.5 mm²?

The nearest AWG size to 2.5 mm² is 14 AWG (2.081 mm²), but 14 AWG is 16.76 % smaller, so it has about 20 % more resistance. The next AWG size with at least 2.5 mm² is 12 AWG (3.309 mm²). Use 12 AWG when the replacement must never be smaller.

The same pattern holds for most metric sizes: the nearest gauge is often the smaller one.

Metric size	Nearest AWG	Next AWG size up	Its resistance vs your cable
1.5 mm²	16 AWG	14 AWG	−27.92 %
2.5 mm²	14 AWG	12 AWG	−24.44 %
4 mm²	12 AWG	10 AWG	−23.97 %
6 mm²	10 AWG	8 AWG	−28.28 %
10 mm²	8 AWG	6 AWG	−24.82 %
16 mm²	6 AWG	4 AWG	−24.35 %

Is 4 mm² the same as 12 AWG?

No. 12 AWG is 3.309 mm², so a 4 mm² cable has 17.28 % less resistance and carries the same current with less voltage drop. Replacing 4 mm² with 12 AWG adds about 21 % resistance. They are often called equivalents, but not closely enough for a voltage drop or ampacity calculation.

Current ratings do not convert with the area. A metric cable’s rating comes from the wiring rules it was made for, and an AWG wire’s from NEC 310.16, so look up the rating in the system you are installing under.

Worked examples

Input	Result
14 AWG	2.081 mm²
12 AWG	3.309 mm²
10 AWG	5.261 mm²
4/0 AWG	107.2 mm²
2.5 mm²	14 AWG (2.081 mm²)
16 mm²	6 AWG (13.3 mm²)

Calculated by the tool above; open it with the same values to see each step.

Questions, briefly answered

What is a circular mil?

The area of a circle one mil (0.001 in) across, or 5.067075 × 10⁻⁴ mm². The Circular mils row shows it for your size, and kcmil (MCM) shows the same figure in thousands.

Can I convert kcmil to mm²?

Yes. Choose “AWG / kcmil to mm²” and pick the kcmil size; 1 kcmil is 0.5067075 mm², so 250 kcmil is 126.7 mm².

What is 6 mm² in AWG?

The nearest gauge is 10 AWG (5.261 mm², 12.31 % smaller). The next size with at least 6 mm² is 8 AWG at 8.366 mm².

How many mm² is 10 gauge wire?

10 AWG is 5.261 mm² (10,383 circular mils) with a solid diameter of 2.588 mm. The metric sizes either side are 6 mm² and 4 mm².

What does a negative resistance percentage mean?

The other size has less resistance than yours because its area is larger. Resistance is inversely proportional to area for the same metal and temperature.

Why does the converter accept a size like 3 mm²?

Some cables and old data sheets use non-standard sizes. 3 mm² converts to 12 AWG as the nearest size (10.29 % larger), and the tool warns that it is not an IEC 60228 size and names 4 mm² as the next standard size up.

What is a kcmil?

Kcmil means thousand circular mils, the unit used for conductors larger than 4/0 AWG. One kcmil is 0.5067 mm2, so a 500 kcmil conductor has a cross-section of about 253 mm2.

Wire Gauge Chart: diameter, area, resistance and weight of every AWG size.
Cable Size Calculator: size a cable in mm² from current and run length.
Voltage Drop Calculator: check the drop on AWG or metric cable.
Wire Size Calculator: the AWG size a load and run length need.
Wire Ampacity Calculator: amps an AWG size can carry under NEC 310.16.
DC Voltage Drop Calculator: 12 V, 24 V and 48 V runs in AWG or mm².
Wire and Cable Calculators: every wire tool on the site.

Updated October 2026