AWG to mm Converter
Professional American Wire Gauge to millimeter diameter conversion with precision measurements, tolerances, and comprehensive wire specifications
AWG to mm Diameter Reference
Complete AWG to mm Diameter Reference
Precision wire diameter specifications with tolerances, insulation dimensions, and typical applications for professional electrical work
| AWG Size | Diameter (mm) | Circumference (mm) | Tolerance | With Insulation (mm) | Typical Applications |
|---|---|---|---|---|---|
| 4/0 (0000) | 11.684 | 36.72 | ±0.05 | 13.5-15.0 | Service entrance, industrial feeders |
| 3/0 (000) | 10.405 | 32.7 | ±0.05 | 12.0-13.5 | Service entrance, large feeders |
| 2/0 (00) | 9.266 | 29.12 | ±0.04 | 10.8-12.0 | Service entrance, sub-panels |
| 1/0 (0) | 8.252 | 25.93 | ±0.04 | 9.8-10.8 | Service entrance, feeders |
| 1 | 7.348 | 23.09 | ±0.04 | 8.8-9.8 | Service entrance, large loads |
| 2 | 6.544 | 20.56 | ±0.03 | 8.0-8.8 | Sub-panels, large appliances |
| 3 | 5.827 | 18.31 | ±0.03 | 7.2-8.0 | Feeders, large circuits |
| 4 | 5.189 | 16.31 | ±0.03 | 6.5-7.2 | Sub-panels, A/C units |
| 5 | 4.621 | 14.52 | ±0.03 | 6.0-6.5 | Large appliances, motors |
| 6 | 4.115 | 12.93 | ±0.02 | 5.5-6.0 | Feeders, large circuits |
| 7 | 3.665 | 11.52 | ±0.02 | 5.0-5.5 | Medium power circuits |
| 8 | 3.264 | 10.26 | ±0.02 | 4.5-5.0 | Sub-panels, large appliances |
| 9 | 2.906 | 9.13 | ±0.02 | 4.2-4.5 | Medium power applications |
| 10 | 2.588 | 8.13 | ±0.02 | 3.8-4.2 | Electric dryers, ranges |
| 11 | 2.305 | 7.24 | ±0.02 | 3.5-3.8 | Medium branch circuits |
| 12 | 2.053 | 6.45 | ±0.01 | 3.2-3.5 | Kitchen circuits, A/C |
| 13 | 1.828 | 5.74 | ±0.01 | 3.0-3.2 | Branch circuits |
| 14 | 1.628 | 5.12 | ±0.01 | 2.8-3.0 | Branch circuits, outlets |
| 15 | 1.45 | 4.56 | ±0.01 | 2.6-2.8 | Lighting circuits |
| 16 | 1.291 | 4.06 | ±0.01 | 2.4-2.6 | Extension cords, outlets |
| 17 | 1.15 | 3.61 | ±0.01 | 2.2-2.4 | Appliance cords |
| 18 | 1.024 | 3.22 | ±0.01 | 2.0-2.2 | Appliance cords, fixtures |
| 19 | 0.912 | 2.87 | ±0.01 | 1.8-2.0 | Control circuits |
| 20 | 0.812 | 2.55 | ±0.01 | 1.6-1.8 | Lighting circuits, controls |
| 22 | 0.644 | 2.02 | ±0.01 | 1.4-1.6 | Control circuits, alarms |
| 24 | 0.511 | 1.61 | ±0.01 | 1.2-1.4 | Signal cables, low power |
| 26 | 0.405 | 1.27 | ±0.005 | 1.0-1.2 | Computer cables, telephone |
| 28 | 0.321 | 1.01 | ±0.005 | 0.8-1.0 | Thermocouple, instrumentation |
| 30 | 0.255 | 0.8 | ±0.005 | 0.6-0.8 | Magnet wire, fine electronics |
Measurement Standards
Standard: ASTM B258-02
Temperature: 20°C (68°F)
Material: Annealed copper
Measurement: Bare conductor
Formula: d = 0.127 × 92^((36-n)/39)
Precision & Tolerance
Large AWG: ±0.05mm (4/0-1)
Medium AWG: ±0.02mm (2-10)
Small AWG: ±0.01mm (12-24)
Fine AWG: ±0.005mm (26-30)
Class: ASTM tolerance class
Insulation Types
Formula and Calculation Explained
The American Wire Gauge (AWG) system is based on a logarithmic scale. The formula to convert an AWG number 'n' to a diameter 'd' in millimeters is:
d(mm) = 0.127 × 92^((36 - n) / 39)
0.127 mm: This is the diameter of an AWG 36 wire, which serves as a base value in the formula.
92: This constant is the ratio of diameters between two reference gauge sizes (AWG -2 and AWG 38, or others).
36: The formula is referenced from AWG 36.
39: There are 39 gauge steps between AWG #36 and AWG #0000 (4/0).
The logarithmic nature means that for every 6-gauge decrease, the wire diameter approximately doubles, and for every 3-gauge decrease, the cross-sectional area approximately doubles.
Practical Considerations for Wire Diameter
Choosing the right wire diameter involves more than just converting AWG to mm. Here are key factors to consider:
Solid vs. Stranded Wire
Solid Wire: Consists of a single, solid core. It offers better conductivity and is more rigid, making it ideal for permanent installations where the wire is not subject to bending or vibration (e.g., in-wall wiring).
Stranded Wire: Composed of multiple smaller wires twisted together. It is more flexible and durable against vibration and flexing, making it suitable for connections to moving parts, patch cords, and applications requiring frequent handling.
The overall diameter of stranded wire is slightly larger than a solid wire of the same AWG size due to air gaps between the strands.
Temperature Derating
A wire's current-carrying capacity (ampacity) decreases as the ambient temperature increases. The insulation material has a maximum temperature rating (e.g., 60°C, 75°C, 90°C). If the ambient temperature is high, you must select a larger diameter wire (lower AWG) to prevent overheating and insulation damage.
National Electrical Code (NEC) tables provide correction factors for various ambient temperatures.
Voltage Drop
Over long distances, the resistance of a wire can cause a significant drop in voltage, reducing the power delivered to the load. To minimize voltage drop, especially for long wire runs, you should use a thicker wire (lower AWG, larger diameter). A voltage drop of 3-5% is generally acceptable for most circuits.
Skin Effect in AC Circuits
At high frequencies, AC current tends to flow on the outer surface (the "skin") of a conductor. This phenomenon, known as the skin effect, reduces the effective cross-sectional area and increases the wire's resistance. For high-frequency applications, this may necessitate using a larger diameter wire or specialized conductors like Litz wire to mitigate the effect.
Wire Measurement Techniques
Professional methods for accurate wire diameter measurement and verification
Calipers
Digital calipers
±0.01mm accuracy
Bare conductor only
Multiple measurements
Micrometer
Precision measurement
±0.001mm accuracy
Laboratory standard
Temperature controlled
Wire Gauge
Quick identification
Field measurement
Standard AWG slots
Portable tool
Calculation
Mathematical formula
Cross-sectional area
Theoretical values
Design reference
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