About the AWG to mm² Converter
This AWG to mm² converter translates American Wire Gauge sizes into the metric cross-sectional area used on European and IEC cable, along with the bare conductor diameter in millimetres and inches, the area in kcmil and the DC resistance of a copper conductor. Switch direction to enter a metric size such as 2.5 mm² and see the exact fractional gauge and the nearest AWG with at least that much copper.
It is useful when you are replacing imported cable, reading a datasheet that lists only one system, choosing crimp terminals, or checking that a speaker, solar or automotive wire is genuinely the size printed on the jacket. A table of every gauge from 4/0 to 40 AWG is included.
Values are for a single solid round conductor; stranded wire of the same gauge has the same copper area but a slightly larger overall diameter. This is a size conversion only — the current a wire may safely carry depends on insulation, installation method and your local electrical code.
How to use the awg to mm² converter
- 1Choose AWG → mm² or mm² → AWG.
- 2Pick the gauge from the list, or type the metric cross-section.
- 3Read the area, diameter, kcmil and copper resistance.
- 4In mm² mode, use the suggested gauge or larger so you never end up with less copper.
- 5Use the chart below to compare neighbouring sizes.
Formula and method
American Wire Gauge is a geometric scale defined so that 36 AWG is 0.005 in (0.127 mm) and 0000 (4/0) is 0.46 in (11.684 mm), with 39 equal ratio steps between them. Each step changes the diameter by a factor of 92^(1/39) ≈ 1.1229, so the area changes by about 26% per gauge and doubles every three gauges. For the aught sizes, 0 is n = 0, 00 is n = −1, 000 is n = −2 and 0000 is n = −3.
Cross-sectional area is π/4 × d². Going the other way, the converter solves the formula for n to give the exact fractional gauge, then rounds down to the smallest whole gauge whose area is at least what you entered. Resistance uses annealed copper at 20 °C (100% IACS, ρ = 1/58 Ω·mm²/m); kcmil is the diameter in mils squared ÷ 1,000.
- n
- AWG number (0 = 1/0, −1 = 2/0, −2 = 3/0, −3 = 4/0)
- d
- Bare conductor diameter in mm
- A
- Cross-sectional area in mm²
- ρ
- Copper resistivity, 0.017241 Ω·mm²/m at 20 °C
Worked examples
12 AWG house wiring in mm²
d = 0.127 × 92^(24/39) = 2.0525 mm, so the area is π/4 × 2.0525² = 3.309 mm². Copper resistance is 17.241 ÷ 3.309 = 5.21 Ω/km, or 1.588 Ω per 1,000 ft. The next standard metric size up is 4 mm².
4/0 battery cable
4/0 is defined as 0.46 in = 11.684 mm, giving π/4 × 11.684² = 107.2 mm². In mils, 460² ÷ 1,000 = 211.6 kcmil.
2.5 mm² European cable to AWG
A 2.5 mm² conductor is 1.784 mm across, which is 13.2 on the AWG scale. Rounding to the larger conductor gives 13 AWG at 2.62 mm²; in practice 12 AWG is the common substitute because odd gauges are rarely stocked.
Frequently asked questions
What is 12 AWG in mm²?+
12 AWG has a cross-section of about 3.31 mm² and a diameter of 2.05 mm. It is larger than 2.5 mm² and smaller than 4 mm² metric cable.
What AWG is 2.5 mm² wire?+
2.5 mm² sits at about 13.2 AWG, between 14 AWG (2.08 mm²) and 12 AWG (3.31 mm²). For an equal-or-larger substitute choose 13 AWG or, more commonly, 12 AWG.
Why does a smaller AWG number mean a thicker wire?+
The gauge numbers came from the number of drawing steps used to pull wire through dies. More passes made thinner wire, so higher numbers are thinner and 4/0 is the thickest standard AWG size.
Does stranded wire have the same AWG size as solid?+
Stranded and solid wire of the same gauge have about the same copper area, but stranded wire is slightly larger in overall diameter because of the gaps between strands.
Can I use this to choose a wire for a circuit?+
Use it to match sizes between systems. How much current a wire can carry depends on insulation temperature rating, bundling, ambient temperature and length, so follow your local electrical code or ampacity tables.