What is the significance of AWG in American power cables, and how can this be converted into cross-sectional area in mm²?

AWG and cross-section: Convert AWG to mm² (table, formula & practice)

Many US power cables, device cables and data cables are marked with AWG. In Europe, on the other hand, the conductor cross-section is usually specified in mm². Here you will find a quick conversion, a clear explanation and typical practical examples.

Rule of thumb:
The smaller the AWG number, the thicker the conductor – and the larger the cross-section.

What does AWG mean?

AWG (American Wire Gauge) is a logarithmic system commonly used in North America to indicate conductor diameter. The ratio between two consecutive AWG levels is constant (39 steps over a ratio of 92:1). Important: AWG describes the conductor – not the insulation thickness.

Important note on current carrying capacity (ampacity):
The cross-section is only one factor. Permissible currents depend, among other things, on the cable type (e.g. SVT/SJT/SJTW), standard/approval (e.g. UL/CSA), ambient temperature, installation type and length. Use the values here as a guide and always check the data sheet/standard for safety-related applications.

AWG in mm²: quick conversion table (common values)

The table shows common sizes as found in US power cables and many cable types. The mm² values can be physically derived from the conductor diameter.

AWG Conductor diameter (mm) Cross-section (mm²) "Close" metric nominal values Typical examples
20 0.812 0.52 0.50 mm² Control/signal cables
18 1.024 0.82 0.75–1.0 mm² Many US power cables (e.g. 18/3)
17 1.150 1.04 1.0 mm² Special appliance cables
16 1.291 1.31 1.5 mm² More powerful device cables
15 1.450 1.65 1.5 mm² Industrial/extension (depending on type)
14 1.628 2.08 2.5 mm² More reserve in terms of performance and length
13 1.828 2.63 2.5 mm² Special cable, rarely used in the consumer sector
12 2.053 3.31 4.0 mm² Higher currents / longer cables

Tip: In Europe, "smooth" nominal values (0.75 / 1.0 / 1.5 / 2.5 / 4.0 mm²) are often used – AWG is often slightly different.

Calculate AWG in mm²: Formula (for technology & data sheets)

The conductor diameter of an AWG conductor can be calculated as follows:

d(mm) = 0,127 · 92^((36 − AWG) / 39)

The cross-section is then calculated as follows:

A(mm²) = π · (d/2)²

Practical application: how to use AWG when selecting cables

US power cables (e.g. 18/3, 16/3)

The specification 18/3 typically means: AWG18 and 3 wires. AWG16 is often chosen for longer cables or higher loads – always depending on the cable type/approval.

LAN/patch cables (e.g. AWG26–AWG23)

For data cables, AWG often refers to the conductor in the wire pairs (e.g. Cat cables). Here, the focus is less on high currents and more on signal quality, attenuation and mechanical robustness.

Why "not exact"?

AWG is a geometric conductor specification. European mm² nominal values are often rounded/standardised. Therefore, "AWG ↔ mm²" is often a very good approximation, but not always 1:1.

FAQ

What is AWG, explained simply?

AWG is a US measurement for conductor thickness. Small number = thick conductor = larger cross-section.

What AWG values are common for US power cables?

AWG18 and AWG16 (e.g. 18/3 or 16/3) are very common. The "right" choice depends on the cable type, approval and conditions of use.

Why do US cables use AWG instead of mm²?

In North America, AWG is the established standard for conductor sizes. In Europe, mm² has become the standard for cross-sectional area.

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