Awg to Mm2 Converter
Convert between American Wire Gauge and metric mm² for electrical wire sizing. Enter values for instant results with step-by-step formulas.
Reviewed by Manoj Kumar, Mathematics Educator
Formula
Diameter (mm) = 0.127 x 92^((36-AWG)/39) | Area (mm2) = PI x (d/2)^2
The AWG wire diameter is calculated using the formula where each gauge step changes the diameter by a constant ratio based on 92 raised to the fractional power determined by the gauge number. The cross-sectional area in mm2 is then derived from the diameter using the standard circle area formula.
Worked Examples
Example 1: Residential Circuit Wire Selection
Problem:A 20-amp kitchen circuit in the US requires AWG 12 wire. What is the equivalent metric wire size for ordering from an international supplier?
Solution:AWG 12 diameter = 0.127 x 92^((36-12)/39) = 2.053 mm\nCross-sectional area = PI x (2.053/2)^2 = 3.309 mm2\nNearest standard metric size: 4 mm2 (rounding up for safety)\nVerification: 4 mm2 provides more capacity than 3.31 mm2
Result:AWG 12 = 3.31 mm2 | Use 4 mm2 metric equivalent (next size up for safety)
Example 2: Industrial Motor Feeder Cable
Problem:A European motor specification calls for 16 mm2 cable. What AWG size should be used in a US installation?
Solution:Find AWG with area closest to but not less than 16 mm2\nAWG 6 = 13.30 mm2 (too small)\nAWG 5 = 16.77 mm2 (adequate)\nAWG 4 = 21.15 mm2 (with extra margin)\nSelect AWG 5 or AWG 4 depending on derating factors
Result:16 mm2 is closest to AWG 5 (16.77 mm2) | AWG 4 (21.15 mm2) provides extra margin
Frequently Asked Questions
What is AWG and how does the wire gauge numbering system work?
AWG (American Wire Gauge) is the standardized wire gauge system used predominantly in North America for measuring the diameter of electrically conducting wire. The numbering system is counterintuitive because larger numbers indicate smaller wire. AWG 40 is extremely thin wire used in electronics, while AWG 0000 (4/0) is thick cable used for heavy electrical service. The system is based on the number of drawing dies the wire was historically pulled through to reach its final diameter. Each step down in gauge number increases the wire diameter by a factor of approximately 1.123, and every 6 gauge steps doubles the wire diameter. Every 3 gauge steps doubles the cross-sectional area, which is the key metric for current-carrying capacity.
How is the AWG to mm2 conversion calculated?
The AWG to mm2 conversion uses a logarithmic formula based on the standardized wire gauge system. The wire diameter in millimeters is calculated as 0.127 times 92 raised to the power of (36 minus the AWG number) divided by 39. The cross-sectional area in mm2 is then calculated using the standard circle area formula (pi times radius squared). For example, AWG 12 wire has a diameter of approximately 2.053 mm and a cross-sectional area of 3.31 mm2. This formula produces exact results for all standard AWG sizes. The relationship is exponential, not linear, which is why you cannot simply interpolate between gauge sizes without using the proper formula.
What are common AWG to mm2 equivalents used in electrical work?
The most commonly used AWG sizes and their metric equivalents are: AWG 14 equals 2.08 mm2 (used for 15-amp residential circuits), AWG 12 equals 3.31 mm2 (used for 20-amp circuits), AWG 10 equals 5.26 mm2 (used for 30-amp circuits like dryers), AWG 8 equals 8.37 mm2 (used for 40-amp circuits like ranges), AWG 6 equals 13.30 mm2 (used for 55-amp circuits), and AWG 4 equals 21.15 mm2 (used for sub-panels). In metric countries, standard wire sizes include 1.5 mm2, 2.5 mm2, 4 mm2, 6 mm2, 10 mm2, 16 mm2, and 25 mm2. These metric sizes do not correspond exactly to AWG sizes, requiring careful selection of the nearest equivalent.
How does wire material affect the AWG to mm2 conversion?
The AWG to mm2 conversion for physical dimensions (diameter and cross-sectional area) is the same regardless of wire material because AWG measures physical size, not electrical properties. However, the practical implications differ significantly between materials. Copper is the most common conductor with a resistivity of 17.241 ohm-mm2/km at 20 degrees Celsius. Aluminum has about 61 percent of copper's conductivity, requiring larger cross-sections for the same current capacity. For example, an aluminum wire must be approximately two AWG sizes larger than copper to carry the same current. Silver has slightly better conductivity than copper but is rarely used for wiring due to cost. When selecting wire size, always consider the conductor material alongside the gauge-to-mm2 conversion.
References
Reviewed by Manoj Kumar, Mathematics Educator · Editorial policy