MM to AWG Conversion: Wire Gauge Guide
Converting millimetres to American Wire Gauge (AWG) is essential for electrical wiring projects, particularly when working with international specifications. AWG is the standardised wire gauge system predominantly used in North America for defining the diameter of round, solid, non-ferrous electrical conductors. This guide provides accurate conversion data between metric measurements (mm and mm²) and AWG sizes, helping you select the correct wire gauge for your electrical installations.
MM to AWG Converter
Standard MM² to AWG Conversion Table
The table below displays the most common conversions between metric cross-sectional area (mm²) and American Wire Gauge sizes. These values represent approximate matches, as AWG measurements don’t align perfectly with metric standards.
| Cross-sectional Area (mm²) | AWG Size | Diameter (mm) | Diameter (inches) |
|---|---|---|---|
| 0.05 | 30 | 0.255 | 0.010 |
| 0.08 | 28 | 0.321 | 0.013 |
| 0.14 | 26 | 0.405 | 0.016 |
| 0.25 | 24 | 0.511 | 0.020 |
| 0.34 | 22 | 0.644 | 0.025 |
| 0.5 | 20 | 0.812 | 0.032 |
| 0.75 | 19 | 0.912 | 0.036 |
| 1.0 | 18 | 1.024 | 0.040 |
| 1.5 | 16 | 1.291 | 0.051 |
| 2.5 | 14 | 1.628 | 0.064 |
| 4.0 | 12 | 2.053 | 0.081 |
| 6.0 | 10 | 2.588 | 0.102 |
| 10 | 8 | 3.264 | 0.128 |
| 16 | 6 | 4.115 | 0.162 |
| 25 | 4 | 5.189 | 0.204 |
| 35 | 2 | 6.544 | 0.258 |
| 50 | 1/0 | 8.251 | 0.325 |
| 70 | 2/0 | 9.266 | 0.365 |
| 95 | 3/0 | 10.40 | 0.410 |
| 120 | 4/0 | 11.68 | 0.460 |
Wire Diameter Comparison
Visual representation helps illustrate the significant differences in wire thickness across common AWG sizes. Below are comparative examples showing relative diameters.
2.588 mm
6 mm²
1.628 mm
2.5 mm²
1.024 mm
1.0 mm²
0.644 mm
0.34 mm²
Conversion Formula
AWG to Diameter (mm):
de>D(mm) = 0.127 × 92^((36 – AWG) / 39)
Diameter to AWG:
de>AWG = 36 – 39 × log₉₂(D(mm) / 0.127)
Where:
- D(mm) = wire diameter in millimetres
- AWG = American Wire Gauge number
- log₉₂ = logarithm base 92
Step-by-Step Conversion Example
Converting 1.5 mm diameter to AWG:
- Start with the formula: AWG = 36 – 39 × log₉₂(D / 0.127)
- Substitute D = 1.5 mm: AWG = 36 – 39 × log₉₂(1.5 / 0.127)
- Calculate the division: 1.5 / 0.127 = 11.81
- Apply logarithm: log₉₂(11.81) ≈ 0.543
- Multiply: 39 × 0.543 = 21.18
- Final result: AWG = 36 – 21.18 = 14.82
- Round to nearest standard: AWG 15
AWG to MM² Quick Reference
This comprehensive table covers the full range of common wire gauges from fine instrumentation wire to heavy power cables.
| AWG Gauge | Area (mm²) | AWG Gauge | Area (mm²) |
|---|---|---|---|
| 30 | 0.05 | 10 | 6.0 |
| 28 | 0.08 | 8 | 10 |
| 26 | 0.14 | 6 | 16 |
| 24 | 0.25 | 4 | 25 |
| 22 | 0.34 | 2 | 35 |
| 20 | 0.5 | 1 | 50 |
| 18 | 1.0 | 1/0 | 50 |
| 16 | 1.5 | 2/0 | 70 |
| 14 | 2.5 | 3/0 | 95 |
| 12 | 4.0 | 4/0 | 120 |
Metric vs AWG Standards
AWG originated in the United States and is based on the number of drawing operations required to produce a specific wire diameter from a standard thickness. The system uses an inverse scale where higher gauge numbers indicate thinner wire. For every increase of 6 gauge numbers, the wire diameter is approximately halved, whilst every 3-gauge increase halves the cross-sectional area.
Metric wire sizing, commonly used in the UK, Europe, and most other regions, specifies wire by its cross-sectional area in square millimetres (mm²). This direct measurement system is more intuitive but requires conversion when working with AWG-specified equipment or following North American electrical codes. There is no exact mathematical relationship between the two systems, making reference tables essential.
Common Wire Gauge Applications
| AWG Size | Metric (mm²) | Typical Applications |
|---|---|---|
| 30-26 | 0.05-0.14 | Instrumentation, thermocouple wire, wrapping wire |
| 24-22 | 0.25-0.34 | Low-voltage control circuits, telephone cables |
| 20-18 | 0.5-1.0 | Doorbells, thermostats, automotive primary wire |
| 16-14 | 1.5-2.5 | Extension leads, lighting circuits, appliance cords |
| 12-10 | 4.0-6.0 | Household wiring, air conditioners, cookers |
| 8-6 | 10-16 | Electric cookers, sub-panels, large appliances |
| 4-2 | 25-35 | Service entrance, sub-feeds, large motors |
| 1/0-4/0 | 50-120 | Main service entrance, industrial feeders |
Frequently Asked Questions
What does AWG stand for?
AWG stands for American Wire Gauge, a standardised system for denoting wire diameter used primarily in North America. The system was developed in the 19th century based on the number of drawing operations needed to produce wire of a given thickness.
Why do higher AWG numbers mean thinner wire?
The AWG system originated from the wire-drawing process. A higher gauge number indicates more drawing operations performed on the wire, resulting in a thinner diameter. This inverse relationship can be confusing but reflects the historical manufacturing process.
Can I convert AWG to mm² exactly?
No exact conversion exists between AWG and metric measurements because they’re based on different mathematical systems. AWG follows a logarithmic scale, whilst metric sizing uses direct area measurements. Conversion tables provide close approximations suitable for practical applications.
What’s the difference between wire diameter and cross-sectional area?
Wire diameter measures the thickness across the wire (in mm or inches), whilst cross-sectional area measures the total surface area of the wire’s circular cross-section (in mm²). The relationship is: Area = π × (Diameter/2)². For electrical applications, cross-sectional area is more relevant as it determines current-carrying capacity.
Should I use AWG or metric sizing in the UK?
The UK primarily uses metric wire sizing (mm²), which is standard throughout Europe under IEC specifications. However, AWG knowledge is valuable when working with imported equipment, North American electrical codes, or international projects where AWG specifications are common.
How does temperature affect wire gauge selection?
Higher temperatures reduce a wire’s current-carrying capacity (ampacity). When selecting wire gauge, consider the ambient temperature and any heat generated by the electrical load. Derating factors apply when wires are bundled together or installed in high-temperature environments.
What is stranded vs solid wire in relation to AWG?
AWG measurements apply to both solid and stranded conductors. For stranded wire, the AWG rating refers to the total cross-sectional area of all strands combined, not individual strand thickness. Stranded wire offers greater flexibility, whilst solid wire is typically used for permanent installations.
Does the wire material affect gauge conversion?
Wire diameter and cross-sectional area remain the same regardless of conductor material (copper, aluminium, etc.). However, material affects current-carrying capacity—aluminium wire requires a larger gauge than copper for the same ampacity due to higher resistance.