AWG to mm Calculator
Convert American Wire Gauge to diameter (mm) and cross-section (mm²).
Reviewed by the ToolNestr Editorial Team — July 2026
How AWG to mm conversion works
The American Wire Gauge (AWG) system is a logarithmic scale where each gauge step corresponds to a fixed ratio in diameter. The standard formula for calculating the diameter of an AWG wire in millimetres is:
where n is the AWG number. For gauges smaller than 0 (1/0, 2/0, 3/0, 4/0), the formula uses negative values: -1 for 1/0, -2 for 2/0, -3 for 3/0, and -4 for 4/0. The cross-sectional area is then calculated from the diameter:
The diameter approximately doubles every 6 AWG steps and the area doubles every 3 AWG steps. For example, 10 AWG has about twice the cross-section of 13 AWG, and 4 AWG has about four times the area of 16 AWG. This makes AWG a convenient system for scaling wire sizes in electrical engineering.
Worked examples
AWG to mm reference table
Common AWG sizes and their equivalent diameter in millimetres and cross-sectional area in mm².
| AWG | Diameter (mm) | Area (mm²) | Typical use |
|---|---|---|---|
| 4/0 (0000) | 11.684 | 107.2 | Service entrance, main feeders |
| 3/0 (000) | 10.404 | 85.0 | Large sub-panels |
| 2/0 (00) | 9.266 | 67.4 | Heavy equipment feeders |
| 1/0 (0) | 8.251 | 53.5 | Large branch circuits |
| 1 | 7.348 | 42.4 | Range, dryer, sub-panels |
| 2 | 6.544 | 33.6 | Main service, EV chargers |
| 4 | 5.189 | 21.2 | Oven, HVAC, large loads |
| 6 | 4.115 | 13.3 | Cooktop, AC unit |
| 8 | 3.264 | 8.37 | Range, water heater |
| 10 | 2.588 | 5.26 | 30 A circuits, EV charger |
| 12 | 2.053 | 3.31 | Lighting, outlets, general |
| 14 | 1.628 | 2.08 | Lighting, 15 A circuits |
| 16 | 1.291 | 1.31 | Extension cords, light duty |
| 18 | 1.024 | 0.823 | Speakers, thermostats |
| 20 | 0.812 | 0.518 | Low-voltage, signal |
| 22 | 0.644 | 0.326 | Data cables, control |
| 24 | 0.511 | 0.205 | Ethernet, sensor wiring |
Bidirectional conversion
Convert AWG to millimetres or enter a diameter in mm to find the nearest standard AWG size. Toggle direction with one click.
Both diameter and area
See the wire diameter in millimetres and the cross-sectional area in mm² simultaneously. Area is calculated from the diameter using the standard circle formula.
Electronics projects
Hobbyists working with metric components can quickly match US-spec AWG wire to metric terminal blocks, PCB traces, and ferrules.
Electrical installations
Electricians working with both imperial and metric wiring standards can verify wire sizes when substituting or sourcing equivalent conductors.
Use cases for AWG to mm conversion
Matching US wire to metric standards
While North America uses AWG for almost all electrical wiring, much of the rest of the world specifies conductor sizes directly in square millimetres. When importing equipment, sourcing wire from international suppliers, or working on projects with mixed standards, you need to convert between AWG and mm. For example, a European terminal block rated for 4 mm² wire accepts conductors equivalent to approximately 10–12 AWG. Knowing the exact conversion prevents undersizing or oversizing connections, both of which can cause poor contact or mechanical stress on terminals.
Choosing wire for current capacity
Although ampacity depends on more than just the cross-sectional area — including insulation type, ambient temperature, bundling, and conductor material — the diameter and area of the conductor are the starting point. A 2.5 mm² wire is roughly 13 AWG and a 6 mm² wire is roughly 9 AWG. When designing a circuit, you look up the required ampacity in your local code table, then find the AWG or mm² size that meets or exceeds that current rating. This calculator helps you move between the two sizing systems when comparing tables from different standards.
Electronics and prototyping
In electronics, breadboard jumpers, prototyping wire, and component leads are often specified in AWG while PCB trace widths are calculated in mm or mm². A typical prototyping wire is 22 AWG (0.64 mm), while a 0.1″ header pin is about 0.64 mm square — matching well to 22 AWG. When designing a PCB that carries a few hundred milliamps, you might use a 0.5 mm trace, which is roughly 24 AWG equivalent. Being able to convert between gauge and metric dimensions helps you choose appropriate wire sizes for your prototypes and ensures compatibility with connectors and terminals.
Automotive and marine wiring
The automotive industry uses a mix of AWG and metric wire sizes depending on the manufacturer and region. A Japanese car might use metric wire sizes while a US car uses AWG. When adding aftermarket accessories or repairing wiring, you need to match the existing wire gauge or choose an appropriate replacement. Battery cables in larger vehicles often use 1/0 or 2/0 AWG (8.25–9.27 mm), while smaller signal wires might be 18–22 AWG. Converting to millimetres gives you a physical sense of the wire size that raw AWG numbers do not always convey.
Tips for working with AWG and mm
Bigger AWG number = thinner wire
This is the most common point of confusion. AWG 22 is much thinner than AWG 10. The scale is inverted: as the gauge number increases, the diameter decreases. A good rule of thumb is that 10 AWG is about the thickness of a typical paperclip, while 22 AWG is about the thickness of a staple wire.
Ampacity depends on more than gauge
The diameter and cross-sectional area determine the wire’s resistance and thus its heat generation, but the actual current-carrying capacity (ampacity) depends on insulation temperature rating, ambient temperature, number of conductors in a bundle, and installation method. Always consult NEC Table 310.16 or equivalent local standards, not just the wire gauge, for final ampacity values.
Use the reference table for common sizes
The AWG to mm reference table above covers the most common gauges from 4/0 down to 24 AWG. For most residential, commercial, and automotive applications, the sizes in this range are all you need. The formula is useful for less common gauges or when you need precise values beyond the table.
Stranded vs solid wire diameter
The diameter given by the AWG formula is for solid wire. Stranded wire has the same cross-sectional area but a slightly larger overall diameter due to the gaps between strands. For stranded wire, the total conductive cross-section matches the solid equivalent, but the physical outer diameter may be 2–10% larger depending on the stranding construction.
Understanding the AWG system
The American Wire Gauge system was developed in 1857 by J. R. Brown and is based on the number of drawing operations needed to reduce a wire from a standard starting size. Each gauge step represents a reduction in diameter of approximately 26%. The system was standardised so that 36 AWG has a diameter of 0.005 inches (0.127 mm) and 0000 (4/0) AWG has a diameter of 0.460 inches (11.684 mm). Between these endpoints, the 39 gauge steps follow a geometric progression: each step multiplies the diameter by the 39th root of 92.
Why the formula uses 92 and 39
The AWG formula d = 0.127 × 92((36 − n) / 39) may look arbitrary, but it derives from two fixed points: the diameter of 36 AWG (0.127 mm) and the diameter of 0000 AWG (11.684 mm, which is 0.127 × 92). The exponent (36 − n) / 39 ensures that 36 AWG gives an exponent of 0 (resulting in 0.127 mm) and 0000 AWG (n = −3 or equivalent to n = −4 depending on convention) reaches the 92 factor. The 39 steps between these two reference points create a smooth logarithmic progression where each gauge step multiplies the diameter by 92^(1/39) ≈ 1.1229, a 12.3% increase for each decrease in gauge number.
Cross-sectional area and current capacity
The cross-sectional area of a wire is proportional to the square of its diameter, so the area doubles every 3 AWG steps. This means 10 AWG (5.26 mm²) has roughly twice the area of 13 AWG (2.62 mm²), and 7 AWG has twice the area of 10 AWG. Since resistance is inversely proportional to area, the resistance halves every 3 AWG sizes. This neat relationship makes mental estimation straightforward: going down 3 gauge numbers doubles the area and halves the resistance, while going up 3 gauge numbers halves the area and doubles the resistance.
How to use the AWG to mm Calculator
Set the direction
Choose AWG → mm to convert a gauge to metric, or mm → AWG to find the nearest standard gauge from a diameter.
Enter the value
Type an AWG number (e.g. 12) or a diameter in mm (e.g. 2.05). Use negative numbers for 1/0 through 4/0: -1, -2, -3, -4.
Read the results
The conversion updates live as you type. See the diameter in mm and cross-sectional area in mm² instantly.
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Frequently asked questions
Is a higher AWG thicker or thinner?
Thinner — AWG 10 is much thicker than AWG 20.
What is AWG 12 in mm?
About 2.05 mm diameter (~3.31 mm² cross-section).
How much current can a gauge carry?
It depends on length, insulation, and standards — use an ampacity chart, not gauge alone.
What about AWG 0 or 00?
AWG 0 (1/0) is ~8.25 mm, 00 (2/0) is ~9.27 mm. This tool supports the standard range including these.
Sources & references
This tool uses standard formulas and reference values from:
- • NFPA 70 — National Electrical Code (NEC), conduit fill, box fill and conductor ampacity. nfpa.org
- • IPC-2221, Generic Standard on Printed Board Design (trace width / current). ipc.org
- • NIST reference constants and unit definitions; IEEE standards where applicable. nist.gov
For educational and preliminary use. Verify against full engineering calculations and the governing standard before any real design.