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

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Converting AWG to mm² – Correctly classifying AWG 18, 16 and 14 for US power cables

For US power cables, North American appliance leads and many international cables, the conductor size is specified not in mm² but in AWG – American Wire Gauge. This often raises the question for procurement, technical departments and project planning: How many mm² do AWG 18, AWG 16 or AWG 14 correspond to?

A mathematical conversion is possible, but AWG and European nominal cross-sections must not simply be equated on a 1:1 basis. Furthermore, the AWG size alone does not determine either the permissible current or the suitability of a complete power cable. Cable type, connectors, temperature, certification, length and application must all be considered together.

Short answer: How many mm² are AWG 18, AWG 16 and AWG 14?

AWG 18
≈ 0.82 mm²
calculated cross-sectional area
AWG 16
≈ 1.31 mm²
calculated cross-sectional area
AWG 14
≈ 2.08 mm²
calculated cross-sectional area
Rule of thumb: The smaller the AWG number, the thicker the conductor and the greater its cross-sectional area.

AWG 18 is not simply ‘0.75 mm²’ – and AWG 16 is not automatically ‘1.5 mm²’

AWG 18 ≈ 0.82 mm² lies, in theoretical terms, between the European nominal cross-sections of 0.75 and 1.0 mm². AWG 16 ≈ 1.31 mm² lies between 1.0 and 1.5 mm². These values are suitable for technical classification, but do not constitute automatic approval for substitution or equivalence.

AWG explained simply: Smaller number = larger conductor

AWG is a logarithmic system for specifying conductor sizes. For European users, the numbering system may seem unfamiliar at first, as the number gets smaller as the conductor size increases.

 
AWG 18
≈ 0.82 mm²
 
AWG 16
≈ 1.31 mm²
 
AWG 14
≈ 2.08 mm²

Schematic illustration of the relative sizes. In the case of flexible stranded conductors, the actual outer diameter of the conductor bundle does not correspond to the nominal diameter of a solid round wire as shown.

AWG 18, AWG 16 and AWG 14 in US power cables

These three sizes are frequently encountered in professional settings in North American connection cables. The examples show the conductor size – not necessarily the permissible current rating of any given cable.

COMMON APPLIANCE CABLE SIZES

AWG 18 ≈ 0.82 mm²

AWG 18 is found in many US appliance and mains cables, for example as 18/3 in 3-core cables or in suitable 2-pole SPT versions.

Classification:
between 0.75 and 1.0 mm²
LARGER CONDUCTOR

AWG 16 ≈ 1.31 mm²

Compared to AWG 18, AWG 16 has a larger copper cross-sectional area and lower conductor resistance under otherwise comparable conditions.

Classification:
between 1.0 and 1.5 mm²
EVEN LARGER CONDUCTOR

AWG 14 ≈ 2.08 mm²

AWG 14 is used with appropriately designed connection cables when a larger conductor cross-section is required. The actual cable current-carrying capacity depends on the product.

Classification:
approx. 2.08 mm² – no 1:1 metric equivalent

AWG in mm² – conversion table for common conductor sizes

The table shows calculated cross-sectional areas. European nominal cross-sections are standardised sizes in their own right and are therefore deliberately not shown as identical AWG equivalents.

AWG Cross-sectional area approx. Metric classification Practical example
20 approx. 0.52 mm² not a direct replacement for 0.50 mm² smaller appliance, control or signal cables
18 approx. 0.82 mm² between 0.75 and 1.0 mm² many US appliance cables, e.g. 18/3
17 approx. 1.04 mm² calculated as close to 1.0 mm² special connection cables
16 approx. 1.31 mm² between 1.0 and 1.5 mm² US appliance cables, e.g. 16/3
14 approx. 2.08 mm² no metric 1:1 equivalent larger conductors in US cables of corresponding design
12 approx. 3.31 mm² between 2.5 and 4.0 mm² Higher requirements, depending on cable type and approval

These values are calculated geometric cross-sectional areas. They are provided for technical guidance only and do not constitute current approval or automatic equivalence to European nominal cross-sections.

What does 18/3 or 16/3 mean on a US power cable?

On US power cables, you will often see specifications such as 18/3 or 16/3. The first number describes the AWG conductor size, whilst the second indicates the number of conductors or wires in the cable.

18
AWG 18
/
3
3 strands
18/3 = three strands of AWG 18.
AWG 18 corresponds to approximately 0.82 mm² per conductor.
16
AWG 16
/
3
3 cores
16/3 = three conductors in AWG 16.
AWG 16 corresponds to approximately 1.31 mm² per conductor.
Important: The notation 18/3 does not automatically contain the same information as a European designation such as 3G1.5. The cable type, protective conductor designation and approval must be clearly indicated separately in the full cable or product designation.

AWG and mm²: Comparing North American and European cable specifications

European and North American connection cables use different labelling systems. A direct comparison is possible, but the specifications must not simply be renamed.

EUROPEAN DESIGNATION
H05VV-F 3G1.5
H05VV-F describes, amongst other things, the cable type, voltage class and materials.
3G1.5 means 3 conductors, including the protective conductor, each with a cross-section of 1.5 mm².
NORTH AMERICAN DESIGNATION
SJT 16/3
SJT refers to the cable construction or cord type.
16/3 means 3 conductors in AWG 16, with a calculated cross-sectional area of approximately 1.31 mm² per conductor.

AWG 18 and AWG 16 correspond to 0.75 / 1.0 / 1.5 mm²

AWG 18 ≈ 0.82 mm² lies, in theoretical terms, between the metric nominal cross-sections of 0.75 and 1.0 mm².
AWG 16 ≈ 1.31 mm² lies, mathematically speaking, between the metric nominal cross-sections of 1.0 and 1.5 mm².

This correspondence is intended for size comparison. For European mains cables, the specific metric nominal cross-sections and the technical specifications of the respective cable are decisive.

Comparing 0.75 mm², 1.0 mm² and 1.5 mm² in power cables

How many amperes can AWG 18, AWG 16 or AWG 14 carry?

This question cannot be answered on the basis of the AWG number alone. The permissible current carrying capacity of a mains cable depends on its overall construction and the relevant product approval.

Cable type, e.g. SPT, SJT, SVT, SJTW
Insulation material and temperature rating
Connectors: mains plug and IEC device-side connector
Approval, e.g. UL / CSA (product-specific)
Application: load, length and operating conditions

Therefore: Do not generalise by saying ‘AWG 18 = x A’, but always use the technical specifications and approval details for the specific cable.

AWG refers only to the conductor size – SPT, SVT, SJT or SJTOW describe the cable type

For a US mains cable, the AWG specification is usually accompanied by a further cable designation. This describes the respective cable or cord type and its design characteristics.

SPT
for example, for suitable parallel 2-pole appliance cables
SVT
flexible cord type; check specific marking and approval
SJT
commonly used for professional 3-core US appliance cables
SJTW / SJTOW
Extended cord variants for appropriately marked operating conditions
Rule of thumb: AWG answers the question ‘What is the conductor size?’. The full cable marking also specifies the cable construction and the applications for which it is approved.

AWG in practice: examples from the DINIC US power cable range

The DINIC range clearly illustrates why AWG must always be considered in conjunction with cable type, connectors and product approval.

Converting AWG to mm²: Formula for geometric comparison

The AWG geometry can be derived mathematically from the AWG number. The diameter formula describes the nominal diameter of a solid round conductor.

1. Calculate the nominal diameter

d (mm) = 0.127 × 92^((36 − AWG) / 39)

2. Calculate the area of the circle

A (mm²) = π · (d / 2)²
Example: AWG 18
Nominal solid round wire diameter approx. 1.024 mm → cross-sectional area approx. 0.82 mm².
Example: AWG 16
Nominal solid round wire diameter approx. 1.291 mm → cross-sectional area approx. 1.31 mm².
Note regarding flexible conductors: A flexible AWG conductor consists of several individual wires. Its actual outer conductor bundle diameter may therefore be greater than the nominal diameter of the corresponding solid round wire. For technical classification purposes, the AWG size or corresponding cross-sectional area remains the decisive factor.

AWG in network and data cables

AWG is not only used for power cables. The conductor size is also frequently specified in AWG for network and data cables. In these applications, signal transmission, attenuation, cable category, shielding and conductor type are also key considerations.

AWG 26 approx. 0.13 mm²
AWG 24 approx. 0.20 mm²
AWG 23 approx. 0.26 mm²

With data cables, too, AWG must not be considered in isolation. Cable category, construction and application are crucial.

Fully specifying US power cables

AWG is only one aspect of product selection. For a complete US power cable, the following points should be agreed upon.

1. Power plug
e.g. NEMA 1-15P or 5-15P
2. Equipment side
e.g. C7, C13, C15 or C19
3. Cable type
e.g. SPT, SJT or SJTOW
4. AWG
e.g. 18, 16 or 14
5. Approval
Check against specific products and markets

Frequently asked questions about AWG and mm²

What does AWG stand for?

AWG stands for American Wire Gauge and refers to a North American system for specifying conductor sizes. The smaller the AWG number, the larger the conductor.

How many mm² is AWG 18?

AWG 18 has a calculated cross-sectional area of approximately 0.82 mm². This falls between the European nominal cross-sections of 0.75 and 1.0 mm².

How many mm² is AWG 16?

AWG 16 has a calculated cross-sectional area of approximately 1.31 mm², which falls between 1.0 and 1.5 mm².

How many mm² is AWG 14?

AWG 14 has a calculated cross-sectional area of approximately 2.08 mm². There is no exactly identical standard European nominal cross-sectional area for this.

Is AWG 18 the same as 0.75 mm²?

No. AWG 18 corresponds to approximately 0.82 mm². 0.75 mm², on the other hand, is a separate metric nominal cross-sectional area. The values are similar, but not identical.

Is AWG 16 the same as 1.5 mm²?

No. AWG 16 corresponds mathematically to approximately 1.31 mm². 1.5 mm² is a larger metric nominal cross-sectional area.

What does 18/3 mean on a US power cable?

18/3 usually means three conductors of AWG 18. The full cable marking must also be taken into account to assess the cable type, protective conductor, temperature rating and approval.

Why does the conductor get larger as the AWG number decreases?

The AWG system is based on a historical and logarithmic scale. Consequently, the numbering runs in the opposite direction to the conductor size: AWG 14 is larger than AWG 16, and AWG 16 is larger than AWG 18.

How many amps can AWG 18 carry?

This cannot be determined simply on the basis of AWG 18. The cable type, insulation, temperature, connectors, certification and application all combine to determine the permissible current-carrying capacity of the specific cable.

What is the difference between AWG and mm²?

AWG is a numbered North American sizing system. mm² directly describes a metric cross-sectional area. AWG can be converted mathematically into mm², but the resulting values are not automatically identical to European nominal cross-sections.

Is the AWG specification sufficient for selecting a US mains cable?

No. In addition, you must check at least the mains plug, device connection, cable type, rated current, length, temperature rating, approval and intended use.

Relevant MAG guides and product ranges

Note: This page is intended for technical guidance and for the theoretical comparison of AWG conductor sizes with metric cross-sectional areas. It does not replace electrical product approval. The markings, technical data, approvals and operating conditions of the specific cable or the complete connection cable are decisive.

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