AWG to sq mm Converter

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Convert American Wire Gauge to square millimetres and back — with conductor diameter, exact cross-sectional area and the nearest standard metric cable size.

Inputs

Conversion

Conversion direction

AWG size

How to use this calculator: AWG to sq mm Converter

Convert American Wire Gauge to square millimetres and back — with conductor diameter, exact cross-sectional area and the nearest standard metric cable size. The example below is calculated by this page's real engine from the displayed inputs.

1Confirm that the AWG to sq mm Converter matches the quantity or design check you need.
2Enter Conversion direction and AWG size using the units printed beside each field.
3Select the applicable Conversion direction and AWG size options; these choices change the calculation method or factors.
4Calculate, then follow the substituted equations in the worked example and compare the result with any stated limit.
5Read the assumptions, warnings and cited references before using the result for a financial, medical or engineering decision.

Input guide and example values

Use values from the same measurement basis and time period. Conditional fields appear only when the related option is selected.

Input	Example value	Why it matters
Conversion direction	AWG → sq mm	Select the option that matches the real installation or scenario.
AWG size	12 AWG	Select the option that matches the real installation or scenario.

Formula inputs & variables for AWG to sq mm Converter

These are the named quantities used by this calculator. When the source formula does not define a mathematical symbol, OneCalcApp keeps the real input label instead of inventing one.

Variable / input	Unit	Meaning in this calculation
Conversion direction	—	Select the option that matches the real installation or scenario.
AWG size	—	Select the option that matches the real installation or scenario.
Cross-sectional area	mm²	Measured or known cross-sectional area used by the calculation engine.

Formula, derivation and worked example

AWG numbers describe a conductor's diameter, not its area — that is the single most common source of error when reading an American cable spec against an IEC one. The gauge scale is reverse-logarithmic: the diameter of gauge n is 0.127 × 92^((36 − n)/39) millimetres, and the cross-sectional area follows from πd²/4. Because area goes with the square of diameter, dropping three gauge numbers doubles the copper, and dropping six quadruples it. This converter reports the gauge number, the conductor diameter and the cross-sectional area as three separate quantities so they are never confused, and it also gives the nearest standard metric cable size you can actually buy.

d(mm) = 0.127 × 92^((36 − n) / 39)

A(mm²) = π/4 × d²

n = 36 − 39 × log₉₂(d / 0.127)

Substitution steps

1. Diameter
0.127 × 92^((36 − n)/39)
= 2.053 mm
2. Area
π/4 × d²
= 3.31 mm²
3. Standard size
next metric size ≥ area
= 4 mm²

Computed example results

Cross-sectional area: 3.31 mm²; 12 AWG
AWG number: 12; gauge index — not a diameter or an area
Conductor diameter: 2.053 mm; 0.0808 in
Area in kcmil: 6.5 kcmil; thousand circular mils — US practice above 4/0
Nearest standard metric cable: 4 mm²; next size up that is actually sold
Resistance (copper, 20 °C): 5.208 Ω/km
Resistance (aluminium, 20 °C): 8.542 Ω/km

Understanding the result

Read the main result together with supporting checks, assumptions, limits and intermediate values.

For a manual check, repeat the first equation, confirm the units and change one input at a time.

Assumptions and calculation scope

Cross-sectional area is assumed to be entered in mm²; converting from another unit before entry avoids changing the numerical meaning of the calculation.
Conversion direction is assumed to match the real case. Choosing a different available option can change the method, factor or interpretation used by this calculator.
AWG to sq mm Converter applies the displayed d(mm) = 0.127 × 92^((36 − n) / 39) relationship to the entered converter inputs. Factors that are not exposed as inputs or stated assumptions are outside this calculator's calculation scope.

Common mistakes when using AWG to sq mm Converter

Do not copy values into AWG to sq mm Converter without checking that each field represents the quantity described by its label and hint.
Do not leave Conversion direction on the default choice unless that choice matches the real scenario; the selected option can change the calculation path or factor.
Do not replace the displayed d(mm) = 0.127 × 92^((36 − n) / 39) relationship with a different convention without also changing the underlying assumptions; compare like-for-like methods when checking the result.
Do not treat Cross-sectional area = 3.31 mm² from the worked example as a universal answer. It belongs to the displayed example inputs and must be recalculated for the actual case.

When the AWG to sq mm Converter is useful

AWG to sq mm Converter is designed for cases where Conversion direction, AWG size are known and you need Cross-sectional area, AWG number, Conductor diameter. The page keeps the live calculator, calculation method and worked example together so the result can be checked instead of treated as a black-box number.

Use the calculator for the scope described by its inputs and notes. The displayed method is d(mm) = 0.127 × 92^((36 − n) / 39). If the real project or decision needs factors that are not represented here, treat the result as an estimate and add the missing checks separately.

Conversion direction and AWG size: what changes the answer

The worked example uses Conversion direction = AWG → sq mm, AWG size = 12 AWG. With those values, Cross-sectional area is 3.31 mm². Changing an input should be interpreted according to that field's unit, range, option and hint rather than by the number alone.

For this calculator, the main input roles are: Conversion direction: Select the option that matches the real installation or scenario. Available choices include AWG → sq mm, sq mm → AWG. AWG size: Select the option that matches the real installation or scenario. Available choices include 4/0 (0000) AWG, 3/0 (000) AWG, 2/0 (00) AWG, 1/0 (0) AWG.

How to sanity-check a AWG to sq mm Converter result

Start by confirming the entered values and units, then compare the substituted working with the displayed formula or calculation steps. Pay particular attention to Cross-sectional area, because it is the first worked-example output shown by the live engine.

Finally, compare the result with the assumptions, warnings and related calculators on this page. A nearby calculator can be useful as a cross-check when it measures the same workflow from a different input or output direction.

Next logical calculator

Continue with Wire Gauge Chart (AWG to mm²)

Useful next check because both tools use AWG size, while Wire Gauge Chart (AWG to mm²) answers a different part of the same workflow.

Open Wire Gauge Chart (AWG to mm²)

Standards, source trail and limitations

References show the method used. Check the current local edition, amendments and project specification before a regulated decision.

Formula

d(mm) = 0.127 × 92^((36 − n) / 39)
A(mm²) = π/4 × d²
n = 36 − 39 × log₉₂(d / 0.127)

Engineering notes

AWG is a diameter scale; mm² is an area. 12 AWG is 2.053 mm in diameter and 3.31 mm² in area — the two numbers are not interchangeable.
Metric cable is sold in fixed steps (1.5, 2.5, 4, 6, 10 mm² …), so an AWG size rarely maps onto an exact metric size. Round up when in doubt.
The table applies to solid conductors. Stranded cable of the same AWG has the same copper area but a slightly larger overall diameter.

AWG to sq mm conversion table

Diameter and area are for solid conductors. The nearest metric size is the standard cable you would buy against that gauge.

AWG	Diameter (mm)	Area (mm²)	Nearest standard metric size
4/0 (0000)	11.684	107.2	120 mm²
3/0 (000)	10.404	85	95 mm²
2/0 (00)	9.266	67.4	70 mm²
1/0 (0)	8.252	53.5	70 mm²
1	7.348	42.4	50 mm²
2	6.544	33.6	35 mm²
4	5.189	21.2	25 mm²
6	4.115	13.3	16 mm²
8	3.264	8.37	10 mm²
10	2.588	5.26	6 mm²
12	2.053	3.31	4 mm²
14	1.628	2.08	2.5 mm²
16	1.291	1.31	1.5 mm²
18	1.024	0.82	1 mm²
20	0.812	0.52	0.75 mm²
22	0.644	0.33	0.5 mm²
24	0.511	0.2	0.5 mm²

AWG number vs diameter vs area

Three different quantities. The AWG number is an index (a label). The diameter is a physical measurement in mm. The cross-sectional area, in mm², is what determines resistance and current capacity. Always compare cables on area or resistance, never on gauge number alone.

Quick metric equivalents

18 AWG ≈ 0.75 mm² · 16 AWG ≈ 1.5 mm² · 14 AWG ≈ 2.5 mm² · 12 AWG ≈ 4 mm² · 10 AWG ≈ 6 mm² · 8 AWG ≈ 10 mm² · 6 AWG ≈ 16 mm² · 4 AWG ≈ 25 mm² · 2 AWG ≈ 35 mm² · 1/0 AWG ≈ 50 mm² · 4/0 AWG ≈ 120 mm².

Kcmil for the very large sizes

Above 4/0 AWG, American practice switches to thousand circular mils (kcmil). 1 kcmil = 0.5067 mm², so 500 kcmil ≈ 253 mm² and 750 kcmil ≈ 380 mm².

Worked example

1Convert 10 AWG to mm²: d = 0.127 × 92^((36 − 10)/39) = 2.588 mm.
2A = π/4 × 2.588² = 5.26 mm².
3Nearest standard metric cable = 6 mm².

Tips

When an AWG size falls between two metric sizes, choose the larger metric size — never the smaller.
Aluminium at the same size carries about 78% of the copper current, so go up roughly one and a half sizes.

Standards & references

ASTM B258 (AWG dimensions)
IEC 60228 (metric conductor classes)

Frequently asked questions

What is 10 AWG in sq mm?

10 AWG is 5.26 mm² with a 2.588 mm conductor diameter. It is normally supplied against 6 mm² metric cable.

What is 4 sq mm in AWG?

4 mm² sits between 12 AWG (3.31 mm²) and 11 AWG (4.17 mm²). It is usually specified as 12 AWG, which is slightly smaller, so check the current rating.

Is AWG a diameter or an area?

AWG defines the conductor diameter. The area in mm² is derived from it with A = πd²/4, which is why the two scales never line up in round numbers.

How do I convert sq mm to AWG?

Get the diameter from d = √(4A/π), then n = 36 − 39 × log₉₂(d/0.127). This converter does it for you and reports the nearest standard gauge.

Why does a higher AWG number mean a thinner wire?

The number originally counted the number of drawing dies the wire passed through — more passes meant a thinner wire, so the scale runs backwards.

Is 2.5 sq mm the same as 14 AWG?

Almost. 14 AWG is 2.08 mm², so 2.5 mm² is about 20% larger. Substituting 2.5 mm² for 14 AWG is safe; the reverse is not.

What inputs does the AWG to sq mm Converter use?

It uses Conversion direction and AWG size. Follow the unit printed for each field and choose any selectable option to match the real scenario.

What does the AWG to sq mm Converter calculate?

It calculates Cross-sectional area, AWG number, Conductor diameter, Area in kcmil, Nearest standard metric cable, Resistance (copper, 20 °C), and Resistance (aluminium, 20 °C). With the displayed default inputs, Cross-sectional area is 3.31 mm².

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